What’s an Amphibian? overview - PowerPoint Presentation

1. What’s an Amphibian? overview

2. Basic Characteristics of AmphibiansBeing tetrapods (4 limbs) that facilitate moving about on land - these limbs evolved from the pectoral and pelvic finsSkin is thin, soft, glandular (lack scales except in the caecilians) - skin of caecilians with scales similar to those of fish.EctothermicBoth gill and lung breathers - usually gills in the larval stage, replaced by lungs in the adult; cutaneous respiration in manyThree-chambered heart with two atria and one ventricle

3. VocabularyEctothermic: Any so-called cold-blooded animal; that is, any animal whose regulation of body temperature depends on external sources, such as sunlight or a heated rock surface.

4. Reproductionfertilization may be internal or externalegg-layers (oviparous) but may have modifications associated with developmentegg anamniotic – doesn’t have a shell but covered with a series of gelatinous layers and are laid in water.hatchling in aquatic larval form which breath by gillsmost larvae herbivorous, some omnivorous to carnivorouslarval stage may last from 10 days to 20+ years

5. Amphibiansunable to regulate body temperatureskin types limit distribution to warm, moist climates (i.e. tropics, subtropics, and temperate zones)most US species in the south; not found in dry areasgenerally limited to freshwater lakes, streams, ponds - none are true marine forms

6. Represented by three sub classesSubclass Labrinthodontia - looked like a salamanderrepresented by genus Ichthyostega (fish with feet or legs)identified by specific labronthodont toothSubclass Lepospondylinamed for vertebral type with three fused partsSubclass Lissamphibia - contains all living specimenswhere living amphibians evolved is not clear - modern (living) amphibians appeared in Triassic Period

7. Three primary orders of Amphibia within the Subclass LissamphibiaCaudata (Urodela) - SalamandersAnura (Salientia) - Frogs and toadsApoda (Gymnophiona) - Caecilians

8. Order Caudata - Salamanders"bearing a tail"~340 species worldwide, 9 Nearctic families(geographical division comprising temperate Greenland and arctic North America), 6 in US - most Holarctic (N. hemisphere)have four limbs usually of equal size, a tail, and elongated bodyskin is smooth and glandular with mucus and poison glandsfound primarily under leaf litter, in soils, or may be fully aquatic

9. Salamandersmost have internal fertilization by way of a spematophore (packet of sperm deposited by the male which is picked up by the female following courtship; gelatinous coating dissolves to release spermall predaceous - none herbivorous: feed on insects, worms, etc.

10. In southern US reproduction occurs primarily in the wintercome out of burrows, mate, and return to burrowseggs develop in pondsincreased rainfall seems to stimulate breedingmost species breed annually although some breed every two years

11. Sexual dimorphism is limitedSexual dimorphism: little differences between males and femalescloacal glands enlarge during reproductive activity to contribute mucus layers to spermatophoremale skin slightly rougher and caudal fins become longerhedonic glands(any of several glands of various salamanders and reptiles that produce a secretion believed to function in sexual attraction and stimulation) in male90% of all salamanders utilize spermatophores for internal fertilization

12. 5 Pathways for Egg and Larva Development1. Both egg and larval stages are aquaticNecturidae, Amphiumidae, most Ambystomatidae permanently aquatic2. Eggs terrestrial, larvae aquaticAmbystoma opacum (marbled salamander) lay eggs in depressions which fill with rainfall; eggs hatch as aquatic larvae3. eggs terrestrial, larvae terrestrial

13. Egg and Larva DevelopmentPlethodontid Desmognathus aeneus - larval form does not feed before developing into adult4. eggs terrestrial with direct developmentPlethodontids which develop from egg directly through larval stage to adult5. eggs retained in the oviduct and fully develop, followed by live birth

14. Reproductive strategies based on site of ovipositionOviposition :to deposit or lay eggs, especially by means of an ovipositor.in open static water (lentic systems) - sirens and salamandridsin running water (lotic systems) - some plethodontidsterrestrial sites - Plethodontids

15. Family Cryptobranchidae - hellbenders

16. Hellbenders"hidden gill"contain the largest living salamandersdistributed in eastern US, Japan, one species in China to 9’Cryptobranchis alleganiensis found in Appalachians of Kentucky/Tennessee

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18. Family Ambystomatidae - mole salamanders

19. Mole Salamandersrestricted to US and Canadarepresented by marbled, tiger, and small-mouthed salamanders

20. Family Amphiumidae - congo eels

21. Species of Congo Eelsonly three species in the worldall are carnivorousnamed for the number of toesAll are found in the United States

22. Two-toed amphiumaThe two-toed amphiuma (Amphiuma means) is a snake-like salamander found chiefly in the southeastern United States. It is commonly, but incorrectly, called "congo snake", "conger eel" or the "blind eel". One of the largest extant species of amphibians in the world, they can grow from 39 to 1,042 g (1.4 to 36.8 oz) in mass and from 34.8 to 116 cm (13.7 to 45.7 in) in length.They have four vestigial legs that end in two or three toes which are virtually useless, and eyes with lids. They are blue-black in color.

23. A.meansThey feed on small fish, crawfish, insect larvae, and even small snakes; they are harmless to humans when left alone, but when disturbed, they can deliver a tough bite, which may lead to a severe infection. Unlike other salamanders, which are mute, A. means gives a clear whistle when disturbed.

24. Amphiuma pholeterThe one-toed amphiuma is considered aquatic, and ranges in coloration from gray-black to purplish-brown. Unlike the other two Amphiuma species which have distinctively lighter undersides, one-toed amphiumas are the same color on both the dorsum (back) and the venter (belly). It can also be distinguished by its cone-shaped head and toe number -- one-toed amphiumas have one toe on each foot as opposed to the two or three exhibited by other Amphiuma species. It is the smallest species in the genus Amphiuma with the average adult size being 8.5 inches (220 mm).

25. One-toed A. means

26. Amphiuma tridactylumThe three-toed amphiuma looks rather eel-like, with an elongate, dark grey-black, or brown colored body, and tiny vestigial legs. They are capable of growing to lengths of 41 inches (1 m). They have small, lidless eyes, and gill slits. They have four tiny legs each with three toes and an average of 62 costal grooves.

27. Family Plethodontidae - lungless salamanders

28. Lungless Salamandersbreath entirely through the skin and floor of the mouthmany New World species which may breed on landany of more than 370 species of lungless amphibians dependent largely on cutaneous respiration (gas exchange through moistened skin). Plethodontidae is the largest group of salamanders, and its members occur predominantly in the Americas from southern Canada to the Amazon basin in Brazil.

29. Family Necturidae (Proteidae) - mudpuppiesTheir popular name derives from the mistaken belief that they are able to bark. They are found in lakes, rivers, and swamps of eastern North America. Species inhabiting the southern United States are commonly called water dogs.Adults range from approximately 20 to 40 cm (8 to 16 inches) in total length. The body is gray or brown and usually has a scattering of blurry blue-black spots. The external gills, retained throughout life, are bright red. The tail is flattened and exhibits dorsal and ventral fins; it is the major locomotor appendage. The legs are short and moderately robust.

30. MudpuppiesMud puppies prefer clear, silt-free water and usually hide during the day under stones or debris. They eat small animals such as crayfish or mollusks and the eggs of other aquatic animals. Fertilization is internal, and the female lays eggs.represented by five species in the US all in the genus Necturuspermanently aquatic salamanders which retain functional gills as adults

31. Mud puppy

32. Family Salamandridae - newts

33. NewtsUS and European distributionrough-skinned with no costal groovesNewts have the ability to regenerate limbs, eyes, spinal cords, hearts, intestines, and upper and lower jaws!Many newts produce toxins in their skin secretions as a defense mechanism against predators.Newts metamorphose through three distinct developmental life stages: aquatic larva, terrestrial juvenile (called an eft), and adult. Adult newts have lizard-like bodies and may be either fully aquatic, living permanently in the water, or semiaquatic, living terrestrially, but returning to the water every year to breed.

34. Family Sirenidae - sirensThere are only three species of sirens. This species ranges from Virginia south along the Atlantic coast through Florida and into the gulf coast of Alabama.This fully aquatic siren is found in a greater variety of habitats than the other sirens, including ditches, streams, rivers, swamps, lakes, ponds, and some bays. They spend most of their time buried in mud or sand.

35. Siren ReproductionSiren reproduction is a mystery because mating has never been observed. The males lack the gland that secretes spermatophores and the females lack a receptacle in which the sperm is stored. This suggests that they practice external fertilization, however, the female lays eggs singly on widely dispersed aquatic plants. This suggests that the eggs were fertilized before they were laid

36. Siren Either sirens have internal fertilization unlike that seen in any other salamander or the male follows the female around during egg-laying, fertilizing each individual egg. Scientists do know that the eggs are laid in either late winter or early spring and the larvae hatch about two months later.

37. SirensSirens are generally regarded as the most primitive of living salamanders although their ecology and natural history are poorly known. They lack hind limbs and are completely aquatic throughout their lives, as evidenced by their external gills.

38. SirensThis salamander can aestivate to survive. If the siren’s body of water dries up it can burrow in the mud bottom and secrete a cocoon of mucus and shed skin that covers its body to prevent water loss. All body functions slow down, some by 70 percent, and it can live for more than a year, until the pond refills with water.When grasped, they commonly emit a yelping sound.

39. Order Anura - frogs and toads~3,400 specieshave four limbs usually of unequal size - hind limbs are elongated and modified for jumpinghead and trunk fused, tail in larval form lost as adultmore widespread than the salamandersvocalizations are restricted primarily to the male for courtship, establishing territories - may be resonated by a vocal pouchmost have external fertilization where eggs and sperm are shed directly into the water - general reproduction patterns follow that of salamanders

40. Generalized reproductive patternmales vocalize to attract females amplexus (clasping of the female by the male for mating) brings the cloacas of the male and female together external fertilization of eggs by sperm; both deposited in the water tadpoles develop - length of development depends on the species metamorphosis adults predaceous - insectivorous/carnivorous

41. Two primary reproductive positionsAxillary - male grasps the female just behind the forelimbs Inguinal - male grasps the female around the waist just in front of the hind limbs remain in position until eggs and sperm are released for fertilization

42. Primary skeletal modifications in Anuransa general reduction in skull and girdle elementspelvic girdle attackes to a single sacral vertebrasingle cervical vertebra (atlas) articulates with two occipital condyles - no second differentiated axisno differentiation in the thoracic and lumbar vertebrae anterior to the urostyle followed by a single sacral vertebraribs if present never articulate with the sternumdistal limb bones fused - tibiofibula and radio-ulnaincreased joints in pelvic limbs to increase jumping ability

43. Family Ascaphidae - tailed frog

44. Tailed Frogrepresented only by Ascaphus truei in mountainous Pacific NWmale retains its tail as an intromittent organ(An intromittent organ is a general term for an external organ of a male organism that is specialized to deliver sperm during copulation) as an adaptation for mating in fast-flowing streams - copulation may last for 24-30 hours, sperm viable for up to 2 years

45. Tailed FrogA flat, toadlike frog with fairly rough skin. The pupil is vertical. The fingertips are hardened like claws to help the frog crawl among rocks on stream bottoms. Lungs are reduced in size to decrease buoyancy, and respiration takes place through the skin.

46. Family Bufonidae - true toads~350 species worldwide - all 17 US species in the genus Bufoskins very warty with partid glands behind the eyes - secretes bad tasting poisonous substance as a protection against predatorsshorter legs designed for hopping rather than leapingtypically burrow at night

47. Family Bufonidae Bufonids are unique among anurans in having a Bidder's organ, a rudimentary ovary that develops at the anterior end of the larval testes of males. Its persistence in adult males is considered by many to be paedomorphic(the retention of juvenile characteristics by an adult). Toads are further diagnosed by an absence of teeth which, though known in some other frogs, appears to have evolved separately in those lineages.

48. Cane Toadstoads have glands behind their eyes that can secrete a burning milky toxincane toads, which can grow as large as a dinner plate, prefer to eat native frogs, small marsupials and snakes.

49. Cane Taod

50. Family Ranidae - true frogssmall to large frogs with long legs and slim waistlarge, distinct eardrumbroadly webbed hind feet and usually with a prominent ridge down each side of the backaquatic to terrestrial with aquatic larvaerepresented by the genus Rana

51. Characteristics that True Frogs sharecharacteristics include horizontal eye pupils, bony breast bones, teeth on the upper jaw, webbed hind feet, and an excellent jumping ability. Other characteristics include a slender waist, dorsolateral folds along their backs, long legs with pointed toes, and a strictly carnivorous diet.

52. Frogs belonging to the Ranidae family are also found in a huge range of sizes. The largest true frog is called the Goliath frog (Conraua goliath) which can measure 12.5 inches long from nose tip to rump and up 24 inches long or more when its legs are stretched out. Goliath frogs can weigh up to 7 pounds and easily dwarf the largest Bullfrog.

53. The goliath frog is the largest living frog on Earth. Specimens can grow up to 32 cm in length from snout to vent, and weigh up to 3.25 kg. This species has a relatively small habitat range in Cameroon and Equatorial Guinea.

54. Microbatrachella capensisThe smallest member of the Ranidae family is the Micro frog (Microbatrachella capensis) which is found in the moist woodlands of South Africa. The size of an adult Micro frog ranges from 0.4 to 0.7 inches from nose tip to rump. This tiny frog is on the critically endangered list as its environment is shrinking due to human encroachment and the introduction of non-native species of plants that use up the water that the Micro frog depends on for breeding.

55. Micro Frog Adult and Baby

56. Micro FrogThe frog has been named after the species of pitcher plant that it needs to breed called Nepenthes ampullaria, one of many pitcher plant species in Borneo. The frogs attach their eggs to the sides of the pitcher, and the tadpoles grow in the watery liquid inside the plant.

57. Order Apoda (Gymnophiona) - Caeciliansname means “without legs” - a worm-like animalsubterranean diggers~160 species restricted to tropics and subtropicseyes may be covered by skin or even bonetentacle of head may serve as a chemosensory organ to detect underground preyvivipary common - young 30-60% of female’s body size when borninitial growth of fetus supported by yolk sac, embryos feed on uterine milk secreted from the epithelial wall of oviduct

58. Caecilians

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60. CaeciliansCaecilians (pronounced ‘seh-SILL-yuns’) are limbless amphibians that on the surface resemble a worm or a snake. The smaller species measure less than three inches, but the largest one (Caecilia thompsoni from Colombia) grows to almost five feet long.

61. Caecilians1) Some have protrusible eyes, others lack them entirely. The word caecilian comes from the Latin “caecus,” which means blind. Some caecilian species are eyeless, while others have small eyes hidden under their skin.2) Caecilians are the only tentacled amphibians. They have short, sensory tentacles located between their eyes and nostrils that help them probe their environment and find prey.

62. Caecilians3. Caecilian mouths are filled with dozens of needle-like teeth. They tend to eat soil-dwelling invertebrates such as worms and termites, but some species may also grab small snakes, frogs, and lizards. No matter what the meal is, it is swallowed whole.4. Most caecilians have two sets of muscles for closing the jaw, as opposed to the single pair most animals possess. These come in handy for burrowing, where they help keep the skull and jaw rigid

63. Caecilians5.Caecilians are the only amphibians to exclusively use internal insemination. Males have a penis-like appendage called a phallodeum, which they insert into the female’s cloaca for mating sessions that can last several hours.6. ) They can give birth to live young. About 25% of caecilian species lay eggs, but the other 75% give birth to already-developed offspring. Before birth, baby caecilians use their special scraping teeth to feed on the lining of their mother’s oviduct.

64. Caecilian mothers have a special way of providing for their young. Some baby caecilians have very odd teeth: short, blunt ones built for scraping and long, curved ones, like hooks. It turns out these teeth serve a unique purpose early in life. For several weeks after birth, the young caecilians stay with their mother. During this time, she grows a thick outer layer of skin that is rich in fat and other nutrients. Her babies use their modified teeth to peel her skin off and eat it. This unusual parental care behavior is known as dermatotrophy and seems to be unique to caecilians