Question

Presence of comb plates is characteristic feature of
a) Porifera
b) Cnidaria
c) Ctenophora
d) Platyhelminthes
e) Annelids

Answer 1

Hint: This phylum shows presence of tissue level of organisation but cnidoblasts are absent in them. These are commonly known as Sea walnuts also.

Complete answer:
Kingdom Animalia is divided into Non chordates and Chordates depending on absence and presence of Notochord.

Phylum Ctenophora is a phylum of Nonchordates.
General characteristics of this phylum is as follows:
>Initially this group was included as a part of Phylum Coelenterates. However these groups do not show >presence of cnidoblasts and hence it is a separate phylum.
>Tentacles may or may not be present and if present they are always in the multiples of two
>These also show the presence of comb plates. These are eight rows of comb like structures present on the medial surface.. The main function is for locomotion
>Tentacles show presence of adhesive cells called colloblasts
>Bioluminescence is an important property seen in ctenophores. This is the property of living organisms to emit light.
>Statocyst is a special sense organ seen in these animals that helps in balancing
>These animals show external fertilisation and are hermaphrodite
>These show indirect development
>Examples: Sea gooseberry, Sea walnuts, etc

Note:Phylum Ctenophora is the first phylum to show the presence of balancing organs.
This phylum is further divided into Class Tentacula and Class Nuda on the basis of presence and absence of tentacles. Beroe is included in Class Nuda.