GENERAL HISTOLOGY

Detailed explanation-1: -Cnidarians have a radially symmetrical cup or bag-like body made up of two layers of cells. they form a link between the smaller plankton and the larger animals.-teardrop-shaped larvae.-a pair of appendages on each body segment.

Detailed explanation-2: -Cnidarians are radially symmetrical (i.e., similar parts are arranged symmetrically around a central axis). They lack cephalization (concentration of sensory organs in a head), their bodies have two cell layers rather than the three of so-called higher animals, and the saclike coelenteron has one opening (the mouth).

Detailed explanation-3: -Most cnidarians have two tissue layers. The outer layer, the ectoderm, has cells that aid in capturing food and cells that secrete mucus. The inner layer, the endoderm, has cells that produce digestive enzymes and break up food particles. The jellylike material between the two layers is called the mesoglea.

Detailed explanation-4: -The cnidarians, or the jellyfish and their kin, are the simplest animal group that displays true tissues, although they possess only two tissue layers.

Detailed explanation-5: -A jelly-like substance called mesoglea lies between the outer and inner layers of the body. There are two basic cnidarian body shapes: a polyp form, which is attached to a surface; and an upside-down free-floating form called a medusa.