Question

Crocodile and penguin are similar to whale and dogfish in which one of the following features?
(A) They have gill slits at some stage
(B) They possess a solid single stranded central nervous system
(C) They lay eggs and guard them till they hatch
(D) They possess bony skeleton

Answer 1

The given animal’s crocodile, penguin, whale and the dogfish belong to the phylum Chordata. The phylum Chordata includes five classes like Reptilia, amphibia, chondrichthyes, agnatha and the class mammalia in it. The animals belonging to these classes have similar characteristics.

Complete answer:
Phylum Chordata:
The animals belonging to this phylum have some peculiar characters at some stages of life. It includes:-
(1) Notochord develops at some stages of the life; these are the rods of cartilages present in the spine that extend inside the body. This notochord helps these organisms to swim in water by flexing its tail.
(2) The second feature is the dorsal neural tube which develops in the spinal cord of the fish and the other vertebrates. This serves as the main communication trunk of this organism.
(3) The pharyngeal slits are formed. In fish, crocodile etc. these silts are modified into the gills
(4) The new tails that develop behind the anus region. This is called the post anus tail.

Hence the correct answer is option(A)

Note: These chordates possess the bilateral body and are deuterostomes. The deuterostomes are the animals that develop the anus before the mouth in the embryo development stage of that organism. And these are characterized by the fluid filled body called coelom.