What is the function of Obelia?
OBELIA LIFE CYCLE The primary function of the medusa is sexual reproduction. Obelia is dioecious as each medusa has reproductive organs of only one sex. There is no difference between the male and female medusae.
What is the function of tentacles in Obelia?
The umbrella shaped creatures have tentacles covered in nematocysts and suctorial pads that assist in capturing prey. Reproduction of Obelia medusae occurs sexually, eggs and sperm uniting to become small larvae surrounded by cilia.
What is the function of the Hydranth in Obelia?
The hydranths are feeding polyps, they feed by capturing minute animals and larvae. Towards the base of the hydrocaulus in the axils of the polyps, are reproductive polyps called blastostyles.
What is the structure of Obelia?
Structure. Through its life cycle, Obelia take two forms: polyp and medusa. They are diploblastic, with two true tissue layers—an epidermis (ectodermis) and a gastrodermis (endodermis)—with a jelly-like mesoglea filling the area between the two true tissue layers. They carry a nerve net with no brain or ganglia.
What is body of Obelia?
Obelia is a very tiny marine hydroid with a height of 2 cm or a little more. The obelia’s body has two kinds of filaments which are vertical hydrocaulus and horizontal hydrorhiza. Obelia’s life cycle begins as hydroid polyps. Hydroid polyps are small, immobile animals that have tentacles and stalks.
What is Hydrotheca of Obelia?
The hydrotheca around each hydranth is bell or goblet-shaped, has no operculum, but does have a diaphragm near the base. The rim of the hydrotheca is smooth or slightly toothed. The perisarc of older parts of the colony turns brown. The hydranths are on slender stalks.
What is Obelia and Aurelia?
Aurelia is genus of scyphozoan jellyfish , commonly called moon jellies . Obelia is a genus of hydrozoans , a class of mainly marine and some fresh water animal species that have both polyp and medusa stages in their life cycle .
What is the habitat of Obelia?
Habit and Habitat: Obelia is typically marine, colonial and sedentary. It is found attached on piles, rocks and sea weeds in shallow water. The polyp represents the asexual phase which is a prominent branched hydroid colony found attached to rocks, stones, shells of animals, wooden pilings etc.
What is difference between jellyfish and obelia?
Obelia refers to a genus of sedentary colonial coelenterates with upright branching stems bearing minute cups in which the polyps sit while jellyfish refers to a free-swimming marine coelenterate with a gelatinous bell- or saucer-shaped body that is typically transparent and has stinging tentacles around the edge.
Is a hydra a polyp?
Hydra are small polyps from 1 to 20 mm in body length. The body is crowned by up to 10 or 12 tentacles. Usually the tentacles are of approximately the same length as the body, but may be somewhat shorter, particularly in the green hydra, and can exceed 20 cm in length in hungry brown hydra in quiet water.
Why is Obelia called Trimorphic?
It is called trimorphic because it has 3 stages in its life and these are polyp medusa and blastostyle.
Through its life cycle, Obelia take two forms: polyp and medusa. They are diploblastic, with two true tissue layers—an epidermis (ectodermis) and a gastrodermis ( endodermis )—with a jelly-like mesoglea filling the area between the two true tissue layers. They carry a nerve net with no brain or ganglia.
What is the generation of Obelia?
There is a distinct alternation of generations in the life- history of Obelia. The fixed colony represents the diploid or asexual generation, reproducing by budding. The medusae derived from the polyp are independent units, living apart, and feeding themselves.
What are the two types of filaments in the Obelia?
The obelia’s body has two kinds of filaments which are vertical hydrocaulus and horizontal hydrorhiza. Obelia’s life cycle begins as hydroid polyps. Hydroid polyps are small, immobile animals that have tentacles and stalks. Their structure resembles sea anemones; hence they are also called sea furs.
What is the manubrium of Obelia?
From the surface of the subumbrellar surface emerges a hanging tube called manubrium bearing a square mouth at its terminal end (Fig. 1.37D). As the medusa of Obelia swims, the umbrella becomes turned inside out, the sub-umbrella then forming the convex surface and the manubrium arising from its apex.