The mesoglea is quite thick. Nematocysts are the only type of cnidocyte present. The medusa is a modified zooid produced as a hollow bud from the coenosarc of the blastostyle in spring and summer.
Draw the specimen and label the body stalk, the tentacles and the mouth. Gonozooids are elongate, lack tentacles or mouth, do not feed, and do not look like flowers.
Commercially prepared slides include only a small piece of the colony and the stolon is rarely present.
The ectoderm covers the bell on all sides, its epitheliomuscular cells are produced into muscle processes which run longitudinally in the manubrium and tentacles.
It leads into the gastrovascular cavity.
Thus, it is rather difficult to distinguish between sexual and asexual generations. They can also form pseudopodia for engulfing food. The members of the Kingdom Animalia are distributed into phyla singular, phylum , which is equivalent to divisions of the Kingdom Plantae.
Laboratory Exercise. Fibres also interconnect the two rings. When germ cells mature, the gonads rupture and spermatozoa and ova are discharged externally into water.
The medusae are dioecious, they have either four testes or four ovaries in the sub-umbrella just below the radial canals. Because, in Obelia, there are no true two generations to alternate each other.
Spirocysts and ptychocysts are found only in Anthozoa. Characteristic of the epidermis, they are also sometimes found in the gastrodermis. Cnidocytes contain an explosive organelle, the cnida, which, upon proper stimulation, inverts and ejects a slender, often barbed and toxic thread in the direction of prey or predator Fig 7-9.
Can you identify the gonads?
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