Question

List the vertebrate groups that have each of the following. a. a skeleton of cartilage b. a two-chambered heart c. amniotic egg d. endothermy e. a four-chambered heart f. a placenta g. lungs supplemented by air sacs

Short answer

a. The class Chondrichthyes, including sharks, rays, and skates, have a skeleton of cartilage. b. The class Amphibia, including frogs, toads, and salamanders, have a two-chambered heart. c. The classes Reptilia (snakes, lizards, turtles) and Aves (eagles, pigeons, hummingbirds) lay amniotic eggs. d. The classes Aves (birds) and Mammalia (mammals) are endothermic. e. The classes Aves (birds) and Mammalia (mammals) have a four-chambered heart. f. The class Mammalia, including most mammals, have a placenta. g. The class Aves (birds) have lungs supplemented by air sacs.

Step-by-step solution

a. Skeleton of cartilage

The vertebrate group that possesses a skeleton made of cartilage is the class Chondrichthyes, which includes cartilaginous fishes such as sharks, rays, and skates.

b. Two-chambered heart

The vertebrate group with a two-chambered heart is the class Amphibia, which includes amphibians such as frogs, toads, and salamanders.

c. Amniotic egg

Vertebrae groups that lay amniotic eggs are reptiles (class Reptilia), which includes animals like snakes, lizards, and turtles, and birds (class Aves), which includes animals like eagles, pigeons, and hummingbirds.

d. Endothermy

The vertebrate groups that are endothermic, meaning they can regulate their body temperature internally, are the class Aves (birds) and class Mammalia (mammals).

e. Four-chambered heart

The vertebrate groups that have a four-chambered heart are the class Aves (birds) and class Mammalia (mammals).

f. Placenta

The vertebrate group that has a placenta is the class Mammalia, which includes animals like humans, dogs, and whales. However, it should be noted that not all mammals have placentas, such as monotremes (platypus and echidna), which lay eggs.

g. Lungs supplemented by air sacs

The vertebrate group that has lungs supplemented by air sacs is the class Aves (birds). This adaptation helps birds with efficient respiration for high-energy activities such as flying.