Which of the following is wrong about Coelenterata? (1) They are aquatic and exclusively marine animals. (2) Cnidarians exhibit tissue level of organisation and are diploblastic. (3) Some Cnidarians exhibit two forms namely Polyp and Medusa. (4) Cnidoblasts are present on tentacles and body.

 Answer:(1) They are aquatic and exclusively marine animals.

   Phylum – Coelenterata (Cnidaria)
They are aquatic, mostly marine, sessile or free-swimming, radially
symmetrical animals (Figure 4.6). The name cnidaria is derived from the

cnidoblasts or cnidocytes (which contain the stinging capsules or

nematocysts) present on the tentacles and the body. Cnidoblasts are used

for anchorage, defense and for the capture of prey (Figure 4.7). Cnidarians

exhibit tissue level of organisation and are diploblastic. They have a central

gastro-vascular cavity with a single opening, mouth on hypostome.

Digestion is extracellular and intracellular. Some of the cnidarians, e.g.,

corals have a skeleton composed of calcium carbonate. Cnidarians exhibit

two basic body forms called polyp and medusa (Figure 4.6). The former

is a sessile and cylindrical form like Hydra, Adamsia, etc. whereas, the

latter is umbrella-shaped and free-swimming like Aurelia or jelly fish.

Those cnidarians which exist in both forms exhibit alternation of

generation (Metagenesis), i.e., polyps produce medusae asexually and

medusae form the polyps sexually (e.g., Obelia).

Examples: Physalia (Portuguese man-of-war), Adamsia (Sea anemone),

Pennatula (Sea-pen), Gorgonia (Sea-fan) and Meandrina (Brain coral).

  

Ctenophores, commonly known as sea walnuts or comb jellies
are exclusively marine.

Subphyla Urochordata and
Cephalochordata are often referred to as
protochordates  and are
exclusively marine.

Echinodermata
These animals have an endoskeleton of calcareous ossicles
and, hence, the name Echinodermata (Spiny bodied). All are marine  .