1. | Gill slits are ventrally placed |
2. | Head and trunk are widened considerably |
3. | Distinct demarcation between body and tail |
4. | Their pectorals fins are distinctly marked off from cylindrical bodies |
1. | Squid, Devil fish, Flying fish, Dogfish |
2. | Apple snail, Pearl oyster, Brittle star, Brain coral |
3. | Sea urchin, Sea lily, Sea cucumber, Sea horse |
4. | Cuttlefish, Sea-hare, Tusk shell, Chiton |
1. | Presence of a swim bladder |
2. | Ventrally located mouth |
3. | Lack of operculum |
4. | Placoid scales |
Assertion (A): | Hemichordata was earlier considered as a sub-phylum under non-chordata but now it is placed as a separate Class under Chordata. |
Reason (R): | Hemichordates have a rudimentary structure in the collar region called stomochord, a structure homologous to notochord. |
1. | Both (A) and (R) are True and (R) correctly explains (A). |
2. | (A) is True but (R) is False. |
3. | Both (A) and (R) are False. |
4. | Both (A) and (R) are True but (R) does not correctly explain (A). |