What are the function of cnidarians?

What are the function of cnidarians?

Respiration and excretion in cnidarians are carried on by individual cells that obtain their oxygen directly from water—either that in the coelenteron or that of the environment—and return metabolic wastes to it. Thus, all physiological functions are carried out at no more than the tissue level of differentiation.

What do cnidocytes do?

Cnidocytes (‘stinging cells’) are specialized cells that define the phylum Cnidaria (sea anemones, jellyfish, corals and hydras). They contain an “explosive” organelle called cnidocyst that acts as a 600 million-years-old microscopic injection system and is important for prey capture and anti-predator defense.

What functions does the coelenteron have?

The cnidarian digestive cavity, called the coelenteron, has a single mouth opening through which food/prey enters and waste is expelled. The coelenteron is considered a gastrovascular cavity because it is where both digestion and gas exchange between the organism’s cells and water in the cavity take place.

What is the job of the nematocysts?

Cnidarians contain specialized cells known as cnidocytes (“stinging cells”) containing organelles called nematocysts (stingers). These cells are present around the mouth and tentacles, and serve to immobilize prey with toxins contained within the cells. Nematocysts contain coiled threads that may bear barbs.

What is the jellyfish life cycle?

Jellyfish have a stalked (polyp) phase, when they are attached to coastal reefs, and a jellyfish (medusa) phase, when they float among the plankton. The medusa is the reproductive stage; their eggs are fertilised internally and develop into free-swimming planula larvae.

Does Coelenterata have body cavity?

Coelenterates have an open body cavity called the gastrovascular cavity. Coelenterates are a term used around the Phylum Cnidaria and Ctenophora.

What kind of body type does a cnidarian have?

Generally speaking, Cnidarians have two body types: the medusa and the polyp. The medusa is the free-swimming version, with the mouth usually pointed downwards, while the polyp is the anchored version with the mouth pointing upwards.

How are nematocysts used in the Cnidaria digestive system?

Lesson Summary. A cnidarian is an invertebrate, usually saltwater-dwelling animal belonging to the phylum Cnidaria. All cnidarians possess stinging cells called nematocysts, which can be used for both protection and helping them to catch food. Cnidarians are carnivores, and some can also consume plant matter.

What kind of meat is eaten in Cnidaria?

The meat consumed varies depending on the size of the species eating it, from microscopic zooplankton (animal larvae) and phytoplankton (plant larvae) to small fish. Some coral and anemones have symbiotic, or mutually beneficial, relationships with certain species of fish.

Where does digestion take place in the Cnidaria?

There is an internal space for digestion called gastrovascular cavity, which opens at one end to form a ‘mouth’. Surrounding the mouth, there is a circle of tentacles to aid in the capture and ingestion of food. 2.