Regular Biology Chapter 31 WAGGY The Amphibians

Chapter Objectives 1. List the characteristics of living amphibians 2. Understand the taxonomy of the amphibians 3. Name the three orders of amphibians 4. Discuss the structure & function of the frogs body

Characteristics of Amphibians Amphibians are vertebrates which mean they have an internal skeletal system a dorsal spinal cord & a skull to protect a developed brain There are about 4,880 species of frogs, toads & salamanders Their skin is thin & must be kept moist to allow for gas exchange Most must have water to complete reproductive cycle

Taxonomy Domain: Eukarya Kingdom: Animalia Phylum: Chordata SubPhylum: Vertebrata Class: Amphibia Order: There are three: 1. Caudata 2. Gymnophiona 3. Anura

Order: Caudata The salamanders have elongated bodies,long tails & moist skin They range in length from a few cm to 1.5 m (4.5 ft) They range from fully aquatic to permanently terrestrial Salamanders are carnivorous & are active mostly at night

Most salamanders live in North America They lay their eggs in water & when they hatch they are in a swimming larval form which then metamorphose into the adult body form

Order: Gymnophiona The caecilians These are highly specialized legless amphibians that resemble small snakes Most live in the tropical regions Range in length from 30cm (12 in) to 1.5 m (4.5 ft) Caecilians are rarely seen & little is known about their behavior

Order: Anura Frogs & toads are found worldwide except for the polar regions Most spend at least a portion of their lives in water - some are completely aquatic Anurans with bumpy skin are typically called toads while those with smooth skin are called frogs

The word anura means tailless reflecting that the adults do not have tails Adults are carnivorous & will eat anything they can catch Frogs & toads are adapted for jumping

The Frog: Skin Serves two important functions: 1. Respiration The skin is moist & permeable to gases & water 2. Protection It is covered with mucous glands to maintain the moistness of the skin & to secrete foul tasting substances to deter predators

The Frog: skeleton The spine is short & rigid The forelimbs absorb the shock of landing The forelimbs attach to a pectoral girdle (the shoulders) The hindlimbs attach to the pelvic girdle Both the pectoral & pelvic girdles transfer weight to the legs which are built to handle the stress of gravity