Amphibians Continued Flashcards
Amphibian Charateristics
Ectothermic (cold-blooded) vertebrates that derive body heat from their environment.
4 limbs, smooth skin and are divided into 3 groups: caecilians, newts and salamanders, and frog and toads.
Typically aquatic as larvae and terrestrial as adults.
They are highly dependent on water and are associated with freshwater habitats — none live in the sea.
They typically produce eggs that lack shells to prevent water loss and have to be laid in water. Eggs hatch into larvae (called tadpoles in frogs and toads) that live in water for an extended period. Larvae undergo a complex transformation, called metamorphosis, in which a number of changes in body from equip them for life as adults in terrestrial habitats. Most importantly, the larval gills are lost and replaced by air-breathing lungs.
In frogs and toads, the tail is reabsorbed during metamorphosis and the limbs develop.
Skin Characteristics
Contains glands, is commonly moist, and lacks scales, feathers, or hair.
Most amphibians have lungs but all, to a greater or lesser extent, take in oxygen through their skin.
The skin is also important for taking in water from the environment and contain numerous pigment cells that give it color.
Many are brightly colored; this is especially common in poisonous species, in which striking colors and skin patterns serve as a warning. In other species, skin coloration provides camouflage or plays a role in mate selection.
Parental care
While many produce very large numbers of eggs that they do not care for, others have evolved parental care in which a small number of eggs are protected by one or both parents.
Parental care is usually provided by the female in caecilians, newts, and salamanders, but in many frogs it is provided by the male.
Lacking a shell, amphibian eggs need protection against dehydration and infection by fungae, as well as from predators.
Order: Gymnophiona (Caecilians)
limbless, wormlike animals that burrow in the soil in forested habitats, although some live in rivers and streams. Confined to the tropical habitats in South America, Africa, and Southeast Asia.
Vary in length from several centimeters to more than 1.5m (5ft).
Fertilization is internal. Some species lay eggs, from which free-living larvae emerge, while in others development through metamorphosis occurs within the mother, who gives birth to small adults.
Caecilians are difficult to observe and their biology is less well known than that of other amphibians
Order: Caudata (Salamanders and newts)
Tailed amphibians that live in cool, shady places and are typically active at night.
Absent from most of Africa and Australia, they occur in temperate and tropical habitats in North and South America, Europe, and Asia.
Fertilization in usually internal. Most species lay eggs but in some the eggs hatch inside the mother, who gives birth to larvae or small adults. The male lacks a penis and sperm is transferred to the female in a special structure called a spermatophore.
Some species are aquatic, others are wholly terrestrial, and others spend their lives partly in water or partly on land.
Order: Anura (Frogs and toads)
Lack tails as adults. Their hind limbs are much larger than their front legs and are adapted for jumping, swimming, and digging.
Most are active at night and communicate by calling.
They occur in temperate and tropical habitats in all continents.
Fertilization is external. Most species lay eggs that hatch into free-swimming tadpoles, which the metamorphose into small adults. In some the eggs develop in or on one of the parents.
Some species spend their lives partly in water and partly on land, some are aquatic throughout their lives, while others are wholly terrestrial.
