All cnidarians are carnivores. Most use their cnidae and associated toxin to
capture food
, although none is known actually to pursue prey. Sessile polyps depend for food on organisms that come into contact with their tentacles.
How do cnidarians eat and excrete waste?
Cnidarians take
in food through their mouths
, which is then digested in the coelenteron. Nutrients are then passed to other areas of the body for use, and waste products are expelled either through the mouth or through surface cells via water circulation.
Are cnidarians filter feeders?
Other filter-feeding cnidarians include sea pens,
sea fans
, plumose anemones, and Xenia.
How do cnidarians capture food and defend themselves?
Cnidarians defend themselves and catch prey
using their tentacles
, which have cells called cnidocytes at their tips.
How do cnidarians feed and digest food?
Cnidarians carry out
extracellular digestion
What type of body form is most often seen on free floating cnidarians?
Two distinct body plans are found in Cnidarians: the polyp or tuliplike “stalk” form and
the medusa or “bell” form
. ((Figure)). An example of the polyp form is found in the genus Hydra, whereas the most typical form of medusa is found in the group called the “sea jellies” (jellyfish).
What is the difference between sponges and cnidarians?
Sponges have multiple cell types that are geared toward executing various metabolic functions. Cnidarians have outer and inner tissue layers sandwiching a noncellular mesoglea. Cnidarians possess a well-formed digestive system and carry out extracellular digestion
What animals eat cnidarians?
Predators of cnidarians include:
sea slugs
, which can incorporate nematocysts into their own bodies for self-defense; starfish, notably the crown of thorns starfish, which can devastate corals; butterfly fish and parrot fish
What do cnidarians use to support their body?
In polyps, the
water-filled coelenteron
acts as a hydrostatic skeleton, which, in concert with the mesoglea, maintains the form of these animals. Muscles in cnidarians are extensions of the bases of ectodermal and endodermal cells.
Do cnidarians have a nervous system?
Cnidarians have
simple nervous systems
and it was probably within this group or a closely-related ancestor that nervous systems first evolved.
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.
What feature of all cnidarians gives them their name?
The name Cnidaria comes from the Greek word “cnidos,” which means stinging nettle. Casually touching many cnidarians will make it clear how they got their name when their
nematocysts eject barbed threads tipped with poison
.
What are 3 defense mechanisms of Cnidaria?
Hard corals have
a skeleton and nematocysts
to protect them, and gorgonians (sea whips) have potent chemical defenses.
What are the three body forms of cnidarians?
Cnidarians have two distinct body plans,
the medusa (a) and the polyp (b)
. All cnidarians have two membrane layers, with a jelly-like mesoglea between them. Animals in this phylum display two distinct morphological body plans: polyp or “stalk” and medusa or “bell” (Figure 2).
Are Coelenterates and cnidarians the same?
Cnidarian, also called coelenterate, any member of the phylum
Cnidaria
(Coelenterata), a group made up of more than 9,000 living species. Mostly marine animals, the cnidarians include the corals, hydras, jellyfish, Portuguese men-of-war, sea anemones, sea pens, sea whips, and sea fans.
What evolutionary advances do cnidarians have over the sponges?
The major evolutionary step that occurred with the phylum cnidaria was the
development of tissue-level organization
. Recall that sponges exhibit cellular-level organization but have no true tissues. A tissue is an aggregation of similar cells that work together to carry out a specific function within the body.
