Question
Question: The group of amniotes includes A. Reptiles and birds B. Birds and Mammals C. Fishes and amphib...
The group of amniotes includes
A. Reptiles and birds
B. Birds and Mammals
C. Fishes and amphibians
D. Reptiles and mammals
Solution
The anamniotes lack the amnion. Apart from this feature, the amniotes are also characterized by laying eggs in water but some of them lay eggs on land.
Complete Answer:
- They are vertebrates that do not belong to the clade Amniota. Amniota is a group of vertebrates that consists of reptiles, birds, and mammals.
- During their embryonic or fetal stage, they have an amnion. The amnion is a membrane that surrounds the embryo or fetus as it grows or develops.
- The amnion and the chorion form the amniotic sac. The sac is fluid-filled and the fluid is referred to as amniotic fluid. This fluid serves as a shock absorber preventing physical injury to the growing fetus.
- Anamniota is a group of vertebrates without amnion (the innermost of the extraembryonic membranes forming a fluid filled sac around the foetus in amniotes). It includes cyclostomes, fishes and amphibians.
Thus, the correct option is C i.e. Fishes and amphibians.
Note: Vertebrates that develop without the extra-embryonic membranes are known as amniotes. They do not belong to a formal classification group, because they are associated by the absence of a characteristic. Among the tetrapods, anamniotes include extinct amphibians and two groups of extinct reptile animals such as anthracosaurs and brachiosaurus.