All cnidarians are carnivores. Most use their cnidae and associated toxin to capture food, although none is known actually to pursue prey . ... Once a food item has been captured, tentacles move it to the mouth, either by bending in that direction or by passing it to tentacles nearer the mouth.
What is the coiled thread with a barb at the end called?
Nematocysts
What organelles do cnidarians capture prey with?
Cnidarians contain specialized cells known as cnidocytes (“stinging cells”), which contain organelles called nematocysts (stingers) . These cells are present around the mouth and tentacles, serving to immobilize prey with toxins contained within the cells.
What are 2 body forms of cnidarians?
They have a simple body consisting of a central gut cavity surrounded by tentacles. 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.
How do cnidarians capture prey and defend themselves?
Cnidarians defend themselves and catch prey using their tentacles , which have cells called cnidocytes at their tips.
Is a jellyfish free swimming for its whole life?
But the early days for jellies are much more sedentary. Juvenile jellyfish exist as polyps and are “bottom living,” Janssen said. They attach to rocks and corals on the ocean floor, sucking up plankton food, similar to sea anemones or coral.
Which shape of cnidarians is umbrella shaped?
Medusa, in zoology, one of two principal body types occurring in members of the invertebrate animal phylum Cnidaria. It is the typical form of the jellyfish. The medusoid body is bell- or umbrella-shaped.
What are the three types of nematocysts?
- Nematocyst. This is the main type, present in all Anthozoa. ...
- Ptychocyst. This puts out a sticky substance. ...
- Spirocyst.
Why is a jellyfish called a medusa?
The shape of this bell is called a medusa because it looks like the evil Medusa in Greek mythology – a woman who had offended the goddess Athena who then changed her hair into snakes and made her face so hideous it turned people into stone.
Is obelia a plant or an animal?
Obelia is a genus of hydrozoans, a class of mainly marine and some freshwater animal species that have both polyp and medusa stages in their life cycle. Hydrozoa belongs to the phylum Cnidaria, which are aquatic (mainly marine) organisms that are relatively simple in structure. Obelia is also called sea fur.
Are jellyfish polyps or medusa?
A polyp is the form that attaches to a surface, while a medusa is the form that is free-floating ; a species of cnidarian
How do jellyfish get pregnant?
Jellyfish reproduction involves several different stages. In the adult, or medusa, stage of a jellyfish, they can reproduce sexually by releasing sperm and eggs into the water , forming a planula. ... The polyps clone themselves and bud, or strobilate, into another stage of jellyfish life, called ephyra.
What eats a jellyfish?
Sea anemones may eat jellyfish that drift into their range. Other predators include tunas, sharks, swordfish, sea turtles and penguins. ... In general however, few animals prey on jellyfish; they can broadly be considered to be top predators in the food chain.
Is a jellyfish radial?
Despite the diversity within the jellyfish clade, Medusozoa, all 200 described jellyfish species exhibit radial symmetry
Is Hydra a polyp or medusa?
Hydra exists in both forms: Polyp and Medusa . These forms are dependent upon nutritional content of the living environment. Medusa is the adult and sexual form whereas Polyp is juvenile and asexual form. Under harsh living conditions and starvation, hydra reproduces sexually.
