Question

List the characteristic features that distinguish cartilaginous fishes with living jawless fishes.

Answer 1

1. Cartilaginous Fishes:

1. These have powerful jaws which help in predation.
2. These are free living predatory fishes.
3. These are advanced over jawless fishes.
4. These have a tough skin covered by dermal.
5. Respiration is by lamelliform gills without operculum.
6. Paired fins are present.
7. Fertilization is internal.
8. Viviparous e.g. Scoliodon

2. Living Jawless Fishes:

1. They do not have jaws and the mouth is circular and suctorial.
2. These are ectoparasites on fishes.
3. These are primitive over cartilaginous fishes.
4. The skin is soft and devoid of scales.
5. These have six to fifteen pairs of gills slits.
6. Paired fins are absent.
7. Fertilization is external.
8. Oviparous, e.g. Lamprey