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Most amphibians - at least, all the ones I know of - start their lives in the water (at least, after they hatch). They then spend time maturing before venturing onto land, where they can breed. The cycle than begins again.
Are there any cases where the reverse is true, i.e. a young amphibian starts life on land before venturing into the water as an adult?
Wikipedia hints that this may be the case, but fails to provide examples:
Amphibians typically start out as larvae living in water, but some species have developed behavioural adaptations to bypass this.
Most amphibians lay their eggs in water and have aquatic larvae that undergo metamorphosis to become terrestrial adults
This suggests clearly that not all of them do so.
Here are a few interesting cases I could think of:
The common midwife toad carry the eggs on their back. The eggs are not necessarily submerged by water then.
To my knowledge, the Seepage salamander have terrestrial larvae but they don't feed before they reach the adult age.
The lungless salamanders has a larval stage that is within the egg. When the egg hatches, the individual that comes out is already an adult.
Arguably, since this frog spends the entire larval stage inside a pitcher plant on land, it has started its life cycle on land.
A group of zoologists with Conservation International say they found the frogs by the side of the road in Borneo, near a national park. They were very hard to locate because of their small size, but the scientists followed the frog's loud calls (you can listen to some here) and discovered them living among pitcher plants. They lay their eggs on the inside of the pitchers, and tadpoles grow up swimming in the tiny pools of rainwater that collect in the bottom of these plants. While most species of pitcher plant are carnivorous, the ones preferred by these tiny frogs only eat leaves - in fact, the frogs most likely help break down the leaf material and aid in the plant's digestion.
The moss froglet is an example of a frog which lays eggs on land and the tadpoles develop over several months in the egg mass amongst moss.
The Moss Froglet is a most unusual frog in that tadpoles develop on land. Breeding occurs from November to February. Four to 16 large eggs are laid in clumps of sphagnum or lichen and the tadpoles develop within the egg. After hatching the tadpoles do not feed, but spend the following 9-10 months of development within a fluid derived from the broken-down egg capsules (a gelatinous mass).
When an amphibian is born, they hatch from an egg that is laid in a pond or in a pool of water. They come out of the egg with gills so that they can breath under the water and they also have fins so that they can swim. They begin their life out looking similar to a fish.
As an amphibian hatches from an egg, they look like a fish and are able to swim and have gills. As they grow, they go through what is called metamorphosis. Metamorphosis is when a body goes through different kinds of changes. The changes that an amphibian’s body makes is important to their survival. They start to grow lungs so that they can breathe out of the water. They also grow legs and then later, they might lose their legs and be a completely different looking type of animal.
All About Amphibians
The word amphibian is a Greek word. It is the combination of the world “amphi,” which means dual, or both kinds and the word “bio,” which means life. The translation would be ‘of both kinds of life’. This definition refers to the fact that most amphibians live their lives in two different stages in two different environments…water and land, first as tadpoles and then as terrestrial adult frogs.
This is true for many species, but there are a lot of amphibians that do not follow this life strategy. Some salamanders do not have an aquatic larval stage. Some amphibians are fully aquatic and do not go through metamorphosis into adults (axolotls).
How many amphibians are there in the world?
As of September 2012, there are 7,037 known amphibian species. They are broken down as follows: Anurans (frogs and toads:) 6,027 in 53 families. Caudata (salamanders): 639 in 10 families. Gymnophiona (Caecilians): 191 in 10 families.
How do amphibians breathe?
Most amphibians breathe through lungs and their skin. Their skin has to stay wet in order for them to absorb oxygen so they secrete mucous to keep their skin moist (If they get too dry, they cannot breathe and will die). Oxygen absorbed through their skin will enter blood vessels right at the skin surface that will circulate the oxygen to the rest of the body. Sometimes more than a quarter of the oxygen they use is absorbed directly through their skin. Tadpoles and some aquatic amphibians have gills like fish that they use to breathe. There are a few amphibians that do not have lungs and only breathe through their skin.
Can amphibians smell?
Yes, amphibians can smell. They have tiny openings on the roof of their mouth called external nares that take in different scents directly into their mouths. The external nares also help them breathe, just like our noses do. In some species, like many salamanders, they rely on chemical cues called pheromones for mating.
Do amphibians have teeth?
Yes, a lot of amphibians have teeth. However, they do not have the same kind of teeth that we have. They have what are called vomerine teeth that are only located on the upper jaw and are only in the front part of the mouth. These teeth are used to hold onto prey and not used to actually chew or tear apart prey. Amphibians swallow their prey whole, so they do not need teeth for chewing. They are called vomerine because they are found in the facial bone called the vomer.
What do amphibians eat?
Amphibians will pretty much eat anything live that they can fit in their mouths! This includes bugs, slugs, snails, other frogs, spiders, worms, mice or even birds and bats (if the frog is big enough and the bird or bat small enough). A few species will eat only one particular food like some smaller frogs might specialize on ants or termites. Some particularly voracious frogs/toads like the cane toad have been known to eat non- live food such as dog or cat food! Aquatic amphibians will eat bugs, other amphibians including tadpoles, fish and small aquatic organisms. There is only one frog species known that is actually a vegetarian: The Brazilian Tree frog eats fruits and berries!
What do tadpoles eat?
Most tadpoles eat plants and algae in the water. They are important grazers in aquatic systems because they help with nutrient recycling and control algae populations, which help to maintain the health of freshwater ecosystems. Sometimes tadpoles will eat each other, especially if food resources are low. Some tadpoles eat insect larvae and tiny organisms that are found in the water.
Are amphibians only active at night?
Although many species are only active at night, there are some that are active during the day. Amphibians are usually active at night because they are harder to see and can avoid being eaten. It is also easier to avoid drying out when the sun isn’t shining down on them. Poisonous amphibians that are brightly colored are often active during the day. Bright colors on an animal will warn predators that they are poisonous, so they do not have to worry about predators. They avoid drying out by living in forests or undergrowth where it is damp and the sun isn’t able to dry them out.
Do amphibians hibernate? What do frogs/salamanders do in winter?
Yes, there are many amphibians that hibernate. Amphibians do not like extreme temperatures. During the cold winter months in non-tropic areas, most amphibians will either hibernate in the mud at the bottom of water or dig down into the ground to hibernate. Some amphibians stow away in cracks in logs or between rocks during the winter. They slow their metabolism and their heartbeats down and survive off stored body reserves throughout the winter. There are some frog species that can even survive freezing temperatures by maintaining a high level of glucose in their blood that acts like antifreeze. Some of the frog will actually freeze, like their bladder, but their blood and vital organs do not freeze. The heart can stop beating and the frog can stop breathing, but it when it thaws out, it will still be alive.
Are all amphibians poisonous?
No, only some species of amphibians are poisonous. Usually they are brightly colored to warn predators of their toxic nature. Most amphibians secrete chemicals from their skin to make them taste icky to predators or make it difficult to handle them. These secretions can be slippery or can be sticky and irritating to the skin.
5. Make a list of amphibians that should be found in your locality. Identify five and tell where you found them. OR Collect pictures or sketch five different amphibians which you can identify and tell where they are found.
An internet search should find a government, or university sponsored list of amphibians in your local area. Alternatively look for an amphibian field guide that focuses on your province, state, country or region. You should define your "locality" in whatever way best matches the list you find. For example:
Expand this section to include more species
Habitat: The cane toad inhabits open grassland and woodland, and has displayed a "distinct preference" for areas that have been modified by humans, such as gardens and drainage ditches. In their native habitats, the toads can be found in subtropical forests.
Type of sexual reproduction: The cane toad is a prolific breeder females lay single-clump spawns with thousands of eggs.
Eating habits: Its reproductive success is partly because of opportunistic feeding: it has a diet, unusual among anurans, of both dead and living matter. Most frogs identify prey by movement, and vision appears to be the primary method by which the cane toad detects prey however, the cane toad can also locate food using its sense of smell. They eat a wide range of material in addition to the normal prey of small rodents, reptiles, other amphibians, birds and a range of invertebrates, they also eat plants, dog food and household refuse.
Diseases and harm to humans: The cane toad has poison glands, and the tadpoles are highly toxic to most animals (including livestock) if ingested. There have even been human deaths due to the consumption of cane toads. The cane toad is now considered a pest and an invasive species in many of its introduced regions of particular concern is its toxic skin, which kills many animals—native predators and otherwise—when ingested. This is a big problem in areas where it has been introduced as local animals are not aware of the danger it poses them.
Prevention: Because of its voracious appetite, the cane toad has been introduced to many regions of the Pacific and the Caribbean islands as a method of agricultural pest control. The cane toad does have its uses including in drugs, as leather, and for scientific research. Florida Fish and Wildlife Conservation Commission recommends residents kill them.
Habitat: both moist and dry savanna, montane grassland, forest margins, and agricultural habitats. It is often found near rivers, where it also breeds. It is not a forest species but in the forest zone it can still be found in degraded habitats and towns (including gardens).
Type of sexual reproduction: lays eggs
Eating habits: bugs etc
Diseases and harm to humans: None really, toads are helpful to humans in general, but an overabundance of frogs made life hard for the Egyptians just before the Exodus.
Amphibians include frogs , toads (actually a family of frogs), and salamanders . Amphibians are vertebrates, so they have a bony skeleton. Most amphibians live part of their lives underwater and part on land. Amphibians reproduce by laying eggs that do not have a soft skin, not a hard shell. Most females lay eggs in the water and the babies, called larvae or tadpoles, live in the water, using gills to breathe and finding food as fish do. As the tadpoles grow, they develop legs and lungs that allow them to live on land. This big change is called "metamorphosis." Even after they change, amphibians still have soft moist skin, and nearly all of them have to live in damp places, so they don't dry out.
All amphibians are predators on other animals and will often eat any animal that is small enough to be swallowed whole. Most can only eat invertebrates, but some larger amphibians will eat small fish, other amphibians, or even small mammals.
All amphibians are cold-blooded, like fish, snakes, lizards, and turtles. Cold-blooded means that the animals cannot control their temperature with body heat, and must use the heat of the sun or their environment to stay warm. Most amphibians live on the ground in wetlands or forests, but some live up in trees, and a few species can survive in deserts and other dry habitats. Most kinds of amphibians live in warm, damp climates, only a few kinds can survive in Michigan.
. "Amphibia" (On-line), Animal Diversity Web. Accessed June 22, 2021 at http://www.biokids.umich.edu/accounts/Amphibia/
BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
Copyright © 2002-2021, The Regents of the University of Michigan. All rights reserved.
Words to Know
Estivation: State of inactivity during the hot, dry months of summer.
Gill: A bodily organ capable of obtaining oxygen from water.
Hibernation: State of rest or inactivity during the cold winter months.
Invertebrate: An animal lacking a spinal column.
Larva: An animal in its early form that does not resemble the parent and must go through metamorphosis, or change, to reach its adult stage.
Vertebrate: An animal having a spinal column.
Not all amphibians follow this pattern of reproduction. Some salamanders live out their entire lives on land, where they give birth to fully formed live young. Others lay their eggs in moist places on the forest floor, where they hatch as tiny versions of the adults. Some newts retain their external gills throughout their lives. The red-spotted newt of eastern North American spends its juvenile stage on land as the red eft, returning to water to develop and live as an adult.
Biology: Semester A Finals
>Nucleus = holds chromosomes has the DNA which are the blueprints for the whole cell.
>Ribosome = Makes protein (Located in the Cytoplasm, near the nucleus.)
>Mitochondria = Converts sugar into energy (ATP is that energy!)
>(The Rough Endoplasmic Reticulum HAS ribosomes, while the Smooth Endoplasmic Reticulum DOES NOT.)
>Endoplasmic Reticulum = Processes the protein
>Golgi Apparatus = Packages and ships proteins and other items.
>You need glucose + oxygen -> carbon dioxide + water + energy (ATP)
>Glycolysis converts glucose into pyruvate
>The Krebs Cycle uses the pyruvate to charge up the batteries (NADH & FADH2)
>NADH & FADH2 hold the electrons. (Once they're used up, they go back into the Krebs Cycle to get recharged.)
>When NADH & FADH2 are uncharges, they become NAD+ and FADH+
>The Electron Transport Chain TRANSPORTS electrons from the NADH & FADH2 (It also just basically converts ELECTRONS to ATP.)
>Metaphase is when the chromosomes line up the middle.
>Anaphase is the sister chromatids separating. (Spindle Fibers latch onto the chromosomes and they rip apart the chromosomes.)
>Telophase is when the nucleus grows.
>Haploid = 1 copy of chromosomes. (Only in sex cells. 23 pairs each HAPLOID from both of your parents create 46 pairs which is DIPLOID)
>This process produces HAPLOID sex cells (sperm and egg)
>Tetrad is the crossover in meiosis.
>Meiosis 1 is exactly like Mitosis.
>When crossing over happens, information gets swapped between the two chromosomes.
>Histones are where the DNA is wrapped around.
>Centromeres are slightly off the center of the chromosomes. (It anchors everything, and that's where the Spindle Fibers latch on.)
>Covalent bonds are really strong bonds that help the structure not fall apart.
>Bases are held by hydrogen bonds.
>DNA is strong enough to not fall apart, but they're weak enough to be unzipped.
>tRNA reads the codons and attaches the amino acids.
>Each 3 letters are CODONS. (Codons are very specific instructions for AMINO ACID.)
>Xylem and Phloem help transport water.
>Gymnosperms make cones. (These do not do seed dispersal as well as Spermatophytes, so they just make lots of themselves and just lay on the floor.)
>Phototropism is the growth towards light.
>Gravitropism is when the roots grow downwards, and the stems grow upwards.
>Thigmotropism is when is moves/grows in response to touch.
>Linnaeus Classification is based on physical attributes and taxon group
>Phylogeny is when you are classifying based on the history of a group's evolution.
>Two animal types in this phylum are Trichoplax adhaerens AND Treptoplax reptans.
>2-3mm in in diameter and have squishy bodies
>Live in tropical and subtropical marine habitats
>Eats by engulfing it's food, a process known as phagocytosis
>Moves with pseudopodia, has a free flow type of movement and are able to change their body shape to help them get around by gliding.
>Reproduce through budding
>Are essentially a clump of cells suspended within a jelly-like substance called mesohyl that holds all the cells together.
>Ostia are those pores on the surface of the sponge are the site of water entry (The water carries with it the sponge's food, which is tiny unicellular organisms, such as plankton and algae.)
>Choanocytes allow nutrients to filter through and feed the sponge.
>Amoebocytes move like amoebas within the mesohyl, picking up nutrients from the choanocytes that digested the food particles. (The amoebocytes deliver the nutrients to the other cells within the sponge. )
>Oscula are the large openings on top of the sponge that allow waste to exit.
>Epidermal Cells are tan colored cells that are tightly together packaged to form providing a protective outer layer for the sponge.
>Sponges reproduce asexually
>Shedding (the process in which sponges can slough off small pieces of their bodies that then grow into adult sponges.)
>Budding (The sponge has an outgrowth that grows until it's big enough to separate from the parent sponge.)
>Gemmule Formation (Are able to form gemmules, which are clusters of amoebocytes covered in a protective coating.)
>Hermaphrodites individual sponges can produce both types of gametes--eggs and sperm.
>Sperm Release sperm cells from one sponge are released and enter another sponge through the same openings that water and food enter through--ostia.
>Egg Fertilization the sperm then pass into the mesohyl, where the eggs are located. The sperm fertilizes the eggs. The eggs then grow into larvae, which are sponge zygotes.
>Opposite their attachment end, or base, are tentacles, which are arranged around the cnidarian's mouth.
>Medusas = umbrella shaped, tentacles dangling beneath the body, circling the mouth,capable of swimming
>Cnidocytes are the stinging cells of cnidarians. (They're also the distinguishing feature
of all animals in the Cnidaria phylum.)
>Nematocyst are tiny coiled barbed harpoons that act as a trigger to release a quick and violent force. (They contain chemicals that are sometimes toxic.)
>The Cnidarian shovels food into it's mouth using their own tentacles.
>Cnidarians can digest food bigger than their own individual cells, with the help of the gastrovascular cavity.
>Gastrovascular Cavity secrete enzymes into the cavity and break down the food.
>The waste exits the mouth which is the same way the food came in.
>There are three classes, hydrozoa, scyphozoa and anthozoa.
>Size can range from 50 micrometers to slightly over 2 millimeters.
>Heads have a "wheel like" appearance, and are covered by "hair like projections" called cilia. (Cilia is also considered to be called "corona" because in latin it means "crown.")
>The trophi is considered to be the only "firm" part of a rotifer's body it is the only part that can fossilize (become a fossil.) The trophi is also considered the "jaws" of the Rotifera.
>The trunk is basically the rotifer's body and it is a extendable, tube-like structure that allows the rotifer to stretch out.
>The final portion of a rotifer's body is the foot. The foot is used to propel itself through it's environment or attach itself to a variety of structures.
>Colonies are groups of rotifers that live in close quarters to each other for a better chance of survival.
>Pharynx is the tube where the food is chewed up.
>Mastax is the digestive tract.
>Rotifers have a compact brain situated just above the mastax nerves start from the brain and stretch out through the animal's body.
>Coelom = a true body cavity containing fluid and lined with mesodermal tissue.
>All mollusks (except bivalves) have a radula, which is a tongue like structure located in the mouth to scape objects for food.
>Almost all mollusks have one or two shells. The shell acts like a strong and hard exoskeleton to support and protect the soft body underneath it.
>The food is broken down and the nutrients are taken up by the cells lining the digestive tract.
>The purpose of the circulatory system is to carry nutrients and oxygen to all the cells within the body.
>The excretory system is involved in releasing liquid waste from the body.
>The respiratory system specializes in taking in oxygen from the environment.
>Gastropods have shells varying on what type, they're terrestrial, they move with their "foot", they (except bivalves) use their radula to eat, and have a pair of tentacles with eyes at the ends that are light and touch sensitive.
>Bivalves have two shells, they live in both fresh and salt water, majority of bivalves are sessile, they lack a radula so they feed with their gills, and they sense the environment with their bundles of nerve cells that are sensitive to light and touch.
>Flatworms (Platyhelminthes) and Roundworms (Nematoda) are the simplest of worms and are parasitic.
>Flatworms are the simplest of all worms the lack respiratory and circulatory systems.
>Calcitic Endoskeleton rich structure is made up of skeletal units called ossicles. (That's what gives them the spiny appearance.)
>Hatch from larvae, and echinoderm larvae has bilateral symmetry because it can be split in half.
>Radially Symmetrical as ADULTS.
>Pentaradial Symmetry (five branching body parts.)
>Water vascular system, which is a network of water vessels.
>Ocean water enters the Echinoderm through the sieve plate, which is a calcium filter that prevents large particles from entering.
>The ocean water moves to the radial canal, which is a pathway that circulates water throughout the Echinoderm's body.
>From the radial canal, smaller water vessels branch throughout the animal's body, leading to the tube feet.
>When ampullae are closed, the water pressure increases and the tube feet extend.
>Echinoderms have mutable collagenous tissue, which can shape the animal into any position and lock. (The locking mechanism is controlled by connective tissue called collagen.)
>Notochords are flexible rod shaped structures (In most structures, the notochord develops into vertebrae.)
>3 Chordate Subphyla Urochordata, Cephlochordata, and Vertebrata
>Members of subphylum Urochordate are all tunicates, which are marine chordates (such as sea squirts) that lack a backbone in adulthood.
>Members of subphylum Cephlochordata are all different species of lancelets (a fish-like chordate). "Cephlochordata" literally means "head vertebrae," which describes the key feature of all lancelets: the backbone extends into the head region.
>Some scientists call members of subphylum Vertebrata "Craniata," since all the animals that belong to this subphylum have a head skeleton, the cranium.
Inside the protective cranium is a well-developed brain.
>In most chordate embryos, the dorsal nerve cord develops into a brain and the spinal nerves (spinal cord).Spinal nerves transport sensory information, such as pain, from the body to the brain.
>Other embryonic structures are the pharyngeal slits, which give rise to structures in a Chordate's head. (For fish they transform into gills, and for humans they develop into ear canals and eustachian tubes.)
>The post anal tail is a muscular extension of the body that runs past the anal opening, where mostly solid waste products exit the chordate's body. (In some chordates, such as humans, the post anal tail is present only in embryonic development.)
>Closed Circulatory System, blood is always enclosed in a vessel. Blood is pumped throughout the chordate's body by a heart.
>One spinal nerve controls a group of skeletal muscles, the myotome. In embryos, myotomes develop into back, abdominal, arm, and leg muscles.
>Jawless Fish = had backbones are the ancestors of all tetrapods
>Jawless Fish evolved first
>Jawed Fish evolutionized next, they began coming on land more and more for shot amounts of time.
>Vertebrates are very much diversified
Present Day Examples of Early Vertebrate Evolution are lampreys and hagfish they obtain the same traits as they did 500 millions years ago.
>BOTH Vertebrates and Invertebrates are:
Most of them reproduce sexually
(Backbone) - All fish have backbones. A backbone is a structure unique to all vertebrates that protects nerves that run along the dorsal (back) region.
(Gill) - Fish breathe using gills. Oxygen is absorbed from water through gills.
(Aquatic Lifestyle) - All fish live in the water. Some may be able to come on land briefly, but even they must return to the water to survive.
(Mostly Ectothermic) - Most fish are cold blooded. They rely on external sources to regulate their body temperature. Some fish are endothermic (create their own body heat), but the majority are not.
(Vocal Cords) - Fish do not have the ability to produce sounds with vocal cords, because they do not have vocal cords. Fish do produce sounds through other methods, though.
What makes bony fish unique:
(Bones) - The skeletons of bony fish are composed of bones that protect internal organs and nerves. In cartilaginous fish, the skeletons are composed of cartilage.
(Bilaterally Flattened) - Bony fish are flattened on both the left and right sides, forming mirror images on their two sides. Most cartilaginous fish are flattened on the bottom, creating two distinct sides - a flat white bottom, where the gills are, and a top with color, where the fins and eyes are.
(Swim Bladder) - The majority of bony fish have swim bladders. Swim bladders are organs that can be filled with air to balance buoyancy.
(3-5 Pairs of Gill Slits) - Bony fishes typically have 3-5 gill slits (for breathing) that are protected by an operculum. An operculum is a protective flap of skin.
(External Fertilization) - Although some reproduce through internal fertilization, the majority reproduce by external fertilization. These fish release gametes (sperm and egg cells) into the surrounding water, allowing them to combine.
(Smooth Scales) - Scales in bony fish tend to be smooth and overlapping. Conversely, most cartilaginous fish have spiny scales.
>What Makes Cartilaginous Fish Unique:
A Cartilage Skeleton
Presence of Spiracles
Presence of Dermal Denticles
Absence of Swim Bladders
(Cartilage) = A firm flexible type of connective tissue. The cartilaginous fish evolved around 395 million years ago. They developed from jawed fish.
(Lobe-fin Fish) = Have fins that are fleshy and extend from the body on a single stalk (not several spines or bones). They evolved close to 419 million years ago. The lungfish is a present-day example.
(Ray-fin Fish) = Webs of skin stretched over bony spines, as opposed to fleshy, lobed fins. Ray-fin fish evolved just over 359 million years. The ocean sunfish is an example that swims the oceans today.
(Spiny Sharks) = A group of fish superficially similar to the sharks of today, but differing in several ways, including having tiny scales covering their skin. Spiny sharks evolved close to 420 million years ago but went extinct 250 million years ago.
(Jawed Fish) = Came out shortly after Jawless Fish. They evolved around 430 million years ago and included a group known as placoderms. First organisms to evolve to jaws.
(Placoderms) = Jawed Fish with armored scales.
>Organisms that ARE NOT fish:
is a mammal
does not have gills
must come to the surface to breathe
is a cnidarian
does not have a backbone
does not have gills
A sea snake
is a reptile
can come onto land
does not have gills
is a crustacean
has an endoskeleton (an external protective layer)
(Jawless Fish) = were the first fish to evolve. They were also the first vertebrates. None of them had jaws and all fed by filtering the water around them. They evolved nearly 530 million years ago. An example of a jawless fish is the lamprey.
(Chimaeras) = Closest living relatives are sharks, even though they branched off from them nearly 400 million years ago. They live in water depths deeper than 200 meters, have smooth skin, and have a venomous spine in front of their dorsal (top,back) fin.
(Sharks) = Aquatic fish with tooth like scales and cartilaginous skeletons. The earliest known sharks evolved more than 420 million years ago, but modern day sharks (like the great white shark) evolved around 35 million years ago. This group also contains the largest fish in the world--the whale shark.
(Skates) = Similar to rays in terms of body shape, evolving around the same time, and being related to sharks. The BIG difference between skates and rays is that rays give birth to live offspring while skates lay eggs.
(Rays) = Flattened bodies and gills on their ventral (bottom) side. Rays like skates, are related to sharks and evolved around 150 million years ago. The major difference between rays and skates are that rays give birth to live offspring while skates lay eggs.
(Actinopterygii) = Fins that have skin stretched over, several spines, a SINGLE dorsal fin. Examples are sunfish, salmon, and pufferfish.
Do any amphibians start their lives on land? - Biology
Amphibians are a class of animals like reptiles, mammals, and birds. They live the first part of their lives in the water and the last part on the land. When they hatch from their eggs, amphibians have gills so they can breathe in the water. They also have fins to help them swim, just like fish. Later, their bodies change, growing legs and lungs enabling them to live on the land. The word "amphibian" means two-lives, one in the water and one on land.
Amphibians are Cold-blooded
Like fish and reptiles, amphibians are cold-blooded. This means their bodies don't automatically regulate their temperature. They must cool off and warm up by using their surroundings.
Growing up from Egg to Adult
Most amphibians hatch from eggs. After they hatch, their bodies are still in the larvae stage. In this stage they are very fish like. They have gills to breathe under water and fins to swim with. As they grow older, their bodies undergo changes called metamorphosis. They can grow lungs to breathe air and limbs for walking on the ground. The transformation isn't the same in all amphibians, but most species go through some sort of metamorphosis.
As an example of metamorphosis, we will look at the frog:
a) after hatching the frog is a tadpole with a tail and gills
b) it becomes a tadpole with two legs
c) a tadpole with four legs and a long tail
d) a froglet with a short tail
e) a full grown frog
- Frogs - Frogs are amphibians of the order anura. They generally have a short body, webbed fingers and toes, bulging eyes, and no tail. Frogs are good jumpers with long powerful legs. Toads are a type of frog. Two species of frogs are the American bullfrog and the poison dart frog.
- Salamanders - Salamanders look a bit like lizards. They have skinny bodies, short legs, and long tails. Salamanders can re-grow lost limbs and other body parts. They like wet, moist areas like wetlands. A newt is a type of salamander.
- Caecilians - Caecilians are amphibians that don't have legs or arms. They look a lot like snakes or worms. Some of them can be long and reach lengths of over 4 feet. They have a strong skull and a pointed nose to help them burrow through dirt and mud.
Amphibians have adapted to live in a number of different habitats including streams, forests, meadows, bogs, swamps, ponds, rainforests, and lakes. Most of them like to live in or near water and in damp areas.
Adult amphibians are carnivores and predators. They eat a variety of food including spiders, beetles, and worms. Some of them, like frogs, have long tongues with sticky ends that they flick out to catch their prey.
The larvae of many amphibians mostly eat plants.
The largest amphibian is the Chinese Giant Salamander. It can grow to 6 feet long and weigh 140 pounds. The largest frog is the Goliath Frog which can grow to 15 inches long (not counting the legs) and weigh over 8 pounds.
The smallest amphibian is a frog called the paedophryne amauensis. It is also the world's smallest vertebrate animal. It is about 0.3 inches long.
What is the Difference Between Reptiles and Amphibians?
While reptiles and amphibians may seem similar to most people, they are really very different groups of organisms that are not even that closely related!
At one time, reptiles and amphibians were zoologically classified as a single group due to some of their similarities and shared characteristics. Herpetology is the branch of zoology that studies reptiles (turtles/tortoises, snakes, lizards, crocodilians, tuataras) and amphibians (frogs/toads, caecilians, salamanders/newts). The word herpetology comes from the Greek work herpes which means “to crawl” and refers to the way these animals move around close to the ground.
Some of the similarities between reptiles and amphibians:
- Ectothermic thermoregulation: Both reptiles and amphibians are ectothermic (sometimes called “cold-blooded”) meaning they must rely upon external sources (the sun) to elevate and help them regulate their body temperature.
- Vertebrates (animals that possess a spinal column): Both reptiles and amphibians are vertebrates possessing a central vertebral column (just like fishes and mammals).
- Skin color alteration: Some reptiles and amphibians are able to alter their skin color by concentrating or dissipating melanin. Altering their skin coloration aids in camouflage and/or can help thermoregulation of body temperature.
- Defensive traits: Both reptiles and amphibians use camouflage, biting and inflating of the body to avoid predation. Some lizards (reptiles) and salamanders (amphibians) have the ability to autotomize their tails which is a voluntary removal of the tail as a defensive response.
- Shedding of skin: Some reptiles, like snakes and lizards, shed their skin, and so do amphibians.
Reptiles and amphibians have major differences in their biology and lifestyles though! In fact, reptiles are much more closely related to birds than they are to amphibians.
Reptiles have keratinized, scaly skin that may be smooth or rough, depending on scale types and their skin is not permeable to water. The keratin that makes up their skin is the same material as mammalian hair and finger nails. This impermeable skin allows reptiles like sea snakes and crocodiles to live in saline [salty] environments. Their skin can be considered mostly waterproof and they do not dry out easily. Reptiles typically must drink water directly to hydrate.
Amphibians have porous skin (meaning that gas exchange occurs through their skin and that they can breathe through their skin without always using their lungs…in fact some salamanders are lungless!). Their skin loses water easily meaning they can dry out and are somewhat dependent on staying in or around moist areas. Their skin is not waterproof, and they are unable to live in salt water environments. Amphibians absorb moisture through their skin by sitting in water rather than by drinking it directly. Many amphibians also have glands in their skin that produce toxins that make them poisonous to eat, as a defense mechanism.
Calumma oshaughnessyi photo by Sara Ruane
Amphibians often live in and around water or moist areas due to the porous nature of their skin, although some amphibians are adapted to dry regions, like desert toads. However, most amphibians need water for at least laying eggs and the larval stage of their life cycle. The word amphibian is Greek for “being with a double life,” meaning they live parts of their lives in water and part on land. Amphibians lay soft gelatinous eggs that are permeable to water and usually in water, where their juveniles hatch. Young amphibians are tadpoles/larvae that are often completely aquatic and have rudimentary gills. As these animals mature, they metamorphose to adult forms and their gills are replaced by lungs.
In contrast, reptiles lay hard shelled or leathery, water-tight (amniotic) eggs and their young hatch as smaller miniature versions of the adults, needing only to gain in size to become adults. There are always exceptions, such as some snakes and lizards that give birth to live young rather than laying eggs.
Bufo alvarius photo by Sara Ruane
It is estimated there are 9,000+ reptiles and 6,000+ amphibians found worldwide and they live on every continent except Antarctica. With such diversity, it is easy to see why reptiles and amphibians are popular study organisms as well as pets to a wide variety of people. Enjoy your herps!
- The Green Iguana (Iguana iguana) and the Tuatara (Sphenodon) have a mysterious “third eye” that is located on the top of their heads. The third eye is thought to be able to tell the difference between light and dark which may aide in escaping predators of above.
- Snakes are all predators. The smallest snake, the thread snakes, eat the eggs and pupae of ants. The largest snakes, like the Anaconda, eat animals as large as deer and wild boar.
- Out of the many snakes in New Jersey, only two are considered venomous. They are the Timber Rattlesnake and the Copperhead. Bites are usually not deadly if treated within a few hours of the bite (at a hospital!). Snakes are very reluctant to bite and will not do so unless stepped on or picked up.
- The Wood Frog, found in NJ, has special proteins and glucose (sugar) in their blood that allows the frog to freeze during the winter without destroying their blood cells.
- Many turtles, crocodiles and alligators lay their eggs in the sand or soil and allow the warmth from the sun to incubate the eggs. In most of these species, the temperature the eggs are most constantly at determine the sex of the baby.
Some info included here is summarized in part from:
Websites to check out for more info:
National Geographic – Reptiles – This website gives good overviews with wonderful pictures: http://animals.nationalgeographic.com/animals/reptiles/
Smithsonian National Zoological Park – Comprehensive information on reptiles: amphibians: http://nationalzoo.si.edu/Animals/ReptilesAmphibians/default.cfm
Smithsonian National Zoological Park –
Animal Diversity Web – Class Reptilia – Includes taxonomy, pictures, and evolution:
Amphibia Web – Concentrates on diversity and conservation efforts: http://amphibiaweb.org/
Sara Ruane, PhD, Assistant Professor, Department of Biological Sciences, Rutgers University-Newark
Lisa Rothenburger, MAT, County 4-H Agent/Associate Professor, Department of 4-H Youth Development, Rutgers Cooperative Extension
Do any amphibians start their lives on land? - Biology
The word ‘amphibian’ in itself gives us a lot of insight on the members of this category. It is derived from the Greek word ‘amphibios’ meaning living a dual life. Amphibians are vertebrates that can survive on both land and water. The common examples of this class include caecilians, frogs, toads and salamanders. Let’s get a closer look at these unique animals.
Following are the characteristics of Amphibians:
- They can live on both land and water
- They are carnivores
- Give birth to young in eggs
- Have moist skin that contain mucus and poison glands
Like reptiles and birds amphibians are also cold-blooded or ectothermic animals. This means they rely on the surrounding environment to maintain their body temperature, unlike mammals which regulate their body temperature internally. These species are active in warm temperatures and get sluggish when it’s cold.
Amphibians begin life underwater and breathe through gills. They gradually move to land on the onset of their adulthood, develop lungs and are the only vertebrates that go through a complete metamorphosis. For example some species of frogs give birth to tadpoles with gills that live underwater till adulthood. However there are other species of frogs that are born looking like miniature versions of their parents equipped with the ability to survive on land, while some species retain their gills for the rest of their lives.
Amphibians prefer the wet and damp areas and can be found thriving around wetlands, shallow ponds and marshes. However they can even adapt to a wide range of habitats including man-made ones.
Amphibians are carnivores both on water and land. In water they consume a wide variety of fish, crustaceans, small reptiles and other amphibians. And their menu on land includes insects like flies and spiders as well as worms.
Most amphibians lay their eggs in freshwater however there are some species that breed in moist environments like burrows and leaf litter. The eggs are covered in a clear, jellylike substance that protects them from dehydration and are fertilized externally. Most amphibians undergo metamorphosis frequently accompanied by abrupt change in habitat and behaviour. They transform from aquatic larvae to a terrestrial form at maturity.
Amphibians do not have scales (in most cases), feathers or hair as in the case of fish, birds and mammals. Their skin is smooth, thin and porous i.e. it allows for molecules and gases to pass through and contains both mucus glands and poison glands. Some species use their moist skins to breathe as well as absorb water.
Amphibians are classified into 3 orders
- Order Anura (Salientia) is coined from the Latin words &ldquoan&rdquo meaning &ldquowithout&rdquo and the Greek word &ldquooura&rdquo meaning &ldquotail&rdquo. This order includes Frogs and Toads. Approximately 4500 species come under this category, making Anura the largest order of the three. They differ from the other two in that they are four legged where the hind legs are longer allowing them to climb and leap. They employ external fertilization. These species are vocal and can makes sounds ranging from squeaks to barks.
- Order Caudata (Urodela) coined from the Latin word &ldquocauda&rdquo meaning &ldquotail&rdquo and covers Salamanders, Newts, Waterdogs, Mudpuppies, Sirens and Amphiuma. This order is comprised of about 500 species of amphibians. The name itself tells you how these amphibians are different from the previous. Well, for a start these guys have tails! Approximately equal to the length of the body and sometimes longer which help them swim well. Their limbs are of equal length used for walking and unlike the anurans aren&rsquot able to jump and climb. They show variation in size and the members of this order are not able to vocalize. An exception to these criteria is the Dicamptodon which can squeak when provoked.
- Order Gymnophiona (Apoda) is derived from the Greek word &ldquogymnos&rdquo meaning &ldquonaked&rdquo and &ldquoophis&rdquo meaning &ldquoserpent&rdquo comprises all Caecilians. Approximately 50 known species of Caecilians come under the order Gymnophiona. They are characterised by long, worm-like segmented bodies and resemble eels or earthworms. They have reduced tails and lack any kind of appendages. They are the only amphibians to possess dermal scales and have almost functionless eyes. Their powerful heads and hardened skulls enable them to burrow deep into the ground surface, one of the reasons they are hardly ever seen and research on them is diminutive.
Surviving in an amphibian&rsquos skin is not a cake walk. They make enemies both on land and water owing to the fact that they spend the first part of their life in water and the latter part on land. They are hunted in all their forms from egg to adult by fish, mammals, wading birds, and reptiles like the snake, aquatic invertebrates like leeches and even by their own kind when food is scarce. So why do all other species pick on the amphibians? Well a few of the reasons are that they have soft, thin skin, they are numerous &ndash larvae and tadpoles are often concentrated and most of them are small to medium size. So what then, does a mother amphibian do to protect her young? She picks a safe spot to lay her eggs which she clusters together and guards, even stringing them along as they&rsquore laid if they have to. Embryos even sense the presence of a predator and can alter the hatching time. The only defence available to the larva is that of hiding or running for cover. They even refrain from schooling together. Some of them handle the stress of being hunted down by developing longer wider tails to increase manoeuvrability. Some adult amphibians stay still and use their cryptic coloration or structure or both to blend in with the surrounding and avoid detection by the predator and others scamper away as quick as they can.
Don&rsquot they just look like a pair of nuts?
Being cornered brings out the best in an amphibian &ndash some will inflate themselves to intimidate their pursuer, or even play dead.
They present colourful parts of their bodies which in the animal world means &ldquoI&rsquom not very tasty. I might just kill you.&rdquo Some actually mean what they display, secreting poisonous toxins through glands on their skin. And if that doesn&rsquot work either, they&rsquoll move in for the attack. Salamander will swish their tails while keeping their bodies motionless. This diverts attention from their bodies and these tails also contain poison from the glands in the dorsum. Some of them even give head butts and if captured they will even sink their teeth into their captor. They use every trick in the book, from vocalization to startle their predator, to scent that makes them seem unappetizing right down to combating with a claw like a third toe as in the case of the African frogs &ndash Ptychadena.
Webbed feet, used to fly. above the treetops so high!
Wallace’s Flying Frog got its name from the British naturalist Alfred Russel Wallace in 1869, who was the first to explain the species. This frog apart from hopping and swimming can also fly. Also known as the “parachute frogs” these amphibians splay their four webbed feet as they leap from branch to branch when threatened. They possess membranes between their toes and loose skin flaps on their sides that catch the air as they fall and helping them glide nearly 50 ft above the ground to a nearby branch or all the way down to land. Their oversized toe pads facilitate a soft landing and even help them stick to tree trunks. His flying genius can be found on the tree tops of the dense tropical jungles of Malaysia and Borneo and descend only to mate or lay eggs. Their staple food is mainly insects.
Say hello to the Cane Toad. This American native was brought to Queensland, Australia in the 1930’s on a mission we like to call Beetle Belittle (note: this is purely our own invention), with an aim to diminish the destructive beetle population. But this little malignant venomous toad had its own wicked scheme in mind and sought only to reproduce and spread themselves across the country, poisoning native species that tried eating them and consequently depleted in number. Same went for the fauna that was preyed on by these toads. And they didn’t stop there, their activities also led to the poisoning of pets and humans alike and also reduced prey populations for native insectivores, such as skinks. With few natural predators (within Australia) to control their expansion these toads plundered pet food from feeding bowls left outside of unsuspecting homes. They started off as a crew of 3000 cadets but their numbers are now well into millions and are expanding to the north-eastern Australia. Cane toads are large, stocky amphibians with dry, warty skin, and are mostly found in southern United States, Central America, and tropical South America where their populations are kept in check by the natural predators around.
Actually it’s a Mudpuppy. And we don’t mean a puppy that loves frolicking in the mud. Mudpuppies, also known as waterdogs, are salamanders that get their name from the squeaky sounds they make - relatively like a dog’s bark. They are one of only a few salamanders that can vocalize and among the largest (they can exceed 16 inches in length) with the average length being 11 inches. Mudpuppies are spared by fishermen who harbor the delusion that these slimy amphibians are poisonous. They are characterised by their bushy, red external gills that they grow as larva and keep all through their lifetime. They have gray or brownish-gray bodies with blue-black spots, flat heads and wide tails accompanied by stubby legs and feet with four distinct toes. They are found at the bottom of rivers, streams, lakes and ponds ranging from east to North Carolina, southern central Canada through the Midwestern United States, and south to Georgia and Mississippi. They hide themselves under rocks, logs and underwater plants and emerge at night, never leaving the water, to feed on anything they can catch, including worms, crayfish and snails. Female mudpuppies guard their large clutch of eggs a trait unique among salamanders.