Tag: animal diversity - i (inverterbrate phyla)

Some animals are three layered with ectoderm, endoderm and mesoderm called triploblastic.  Ctenophores have two main layers of cells that sandwich a middle layer of jelly-like material, which is called the mesoglea. So, even though the layers of tisse are diploblastic the presence of the third jelly-like layer gives them an intermediate stage.

Ctenophores have colloblast in their tentacles to capture/ disarm their prey as opposed to cnidarians like jelly fish having Cnidoblasts doing the same function.

The loose layer of jelly-like substance in Ctenophores is mesoglea which are composed of muscle bundles and nerve fibres that lie under the epethelial cells. They are hydrostatic and have elastic cells along with amoebocytes that have a role in phagocytosis, 

Biradial symmetry is a combination of radial and bilateral symmetry, as in the ctenophores. Here, the body components are arranged with similar parts on either side of a central axis, and each of the four sides of the body is identical to the opposite side but different from the adjacent side. Also, Cnidblasts being exclusive Cnidarian character does not exist in Ctenophora.

In Ctenophores, the digestion is predominantly completed in the stomadaeum(extracellular). The undigested food passes out either throught the mouth or the anal pores. 

Statocysts are a balance organ present in ctenophores. This provides equilibriuim for the organism while swimming. These statocysts are situated away from the oral or mouth region also called the aboral region. 

Ctenophores are cylindrical/flat with a biradially symmetrical body along an oral-aboral axis. Biradial symmetry refers to the type of symmetry which is the combination of both radial and bilateral.

Boroe is a transparent comb jelly with sac-like body with a mouth on one side and gonads internally present. However, it lacks any tentacles. So, the correct answer is 'Tentacles'.