Question

Tissue level of organization is found in:
(a)Sea cucumber
(b)Glass sponge
(c)Sea anemone
(d)Comb jelly

Answer 1

Hint: They are a phylum of invertebrate animals known as ctenophore living in marine waters. These are the largest water animals to swim with the help of cilia and species of ctenophores can be a few millimeters to 1.5 m.

Complete answer:
The scientific name of comb jelly is ctenophore and the body consists of two layers of cells and they are Epidermis and the Gastrodermis. Between these two layers is a poorly defined third layer known as Mesoglea and it doesn’t have a coelom. They show tissue level of organization and have no complex organs present in the organism. The comb jellies have eight rows of sets of cilia and are known as the costa. They use this to maintain a correct orientation and to swim in the water, though they use the vertical moment for active control. The sideways flattened species can swim using undulations of their ribbon-like bodies and costa. These species are mostly globular and have a mouth at one side and an anus at the other. The gut runs go through these two. Many canals inside the organism leave the stomach and reach out to the costa. Comb jellies release indigestible particles from pores on the rear end and have a sticky cell but the tentacles don't sting.

So, the correct option is 'comb jelly'.

Note: Most of the Ctenophora are hermaphroditic which means they have both male and female reproductive organs and very few species can reproduce asexually. Eggs and sperm are released into the water where the fertilization occurs and an ovoid larva develops which is known as Cydippid larvae. The larvae grow into a new Comb Jelly mostly but in sideways flattened species like Cestum, a sort of metamorphosis is observed.