They contract
their hollow, saucer-shaped bodies (called bells) to force water out
, which propels them forward. Their long. tentacle-like arms, which trail out behind them, are used to sting and capture prey.
Are Cnidaria motile?
Animals in this phylum display two distinct morphological body plans: polyp or “stalk” and medusa or “bell”. …
Medusa forms are motile
, with the mouth and tentacles hanging down from an umbrella-shaped bell. Cnidarian morphology: Cnidarians have two distinct body plans, the medusa (a) and the polyp (b).
How do cnidarians move quizlet?
How do cnidarians move? Since Cnidarians do not have a mesoderm, they do not have any true muscle. They move
by epithelial muscular cells
(cells in the epidermis that can contract and are made up myosin and actin.
What body form do cnidarians move?
Jellyfish swim using a kind of jet propulsion. They contract their
hollow, saucer-shaped bodies (called bells)
to force water out, which propels them forward. Their long. tentacle-like arms, which trail out behind them, are used to sting and capture prey.
What is the locomotion of cnidarians?
Medusae
swim by jet propulsion
(see below Tissues and muscles). However, most do so weakly and are carried passively by currents over long distances. Polyps are generally sedentary.
What allows cnidarians to be able to bend in different directions?
What allows cnidarians to be able to bend in different directions?
The have muscles
. How do nerve cells work with muscle cells to give the cnidarian movement? They have electrical pulses.
What opening the cnidarians use to remove the 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.
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 is the term for the jelly-like layer of cnidarians?
All cnidarians have two tissue layers. The outer layer is called the epidermis, whereas the inner layer is called the gastrodermis and lines the digestive cavity. Between these two layers is a non-living, jelly-like
mesoglea
.
What are the 3 steps for the life cycle of most cnidarians?
Cnidarians all have a life cycle of two forms. One is a free-swimming jellyfish medusa stage and the
second is an attached polyp stage
.
Do cnidarians have a brain?
Cnidaria do not have a brain or groups of nerve cells
(“ganglia”). The nervous system is a decentralized network (‘nerve net’), with one or two nets present. They do not have a head, but they have a mouth, surrounded by a crown of tentacles. The tentacles are covered with stinging cells (nematocysts).
Are sexes separate in cnidaria?
Cnidarians have separate sexes
and have a lifecycle that involves morphologically distinct forms. These animals also show two distinct morphological forms—medusoid and polypoid—at various stages in their lifecycle.
How fast are nematocysts?
They show discharge kinetics of nematocysts in Hydra to be as
short as 700 nanoseconds
, creating an acceleration of up to 5,410,000 g.
How long can a Praya’s body extend making it the world’s longest predator?
How long can a Praya’s body extend, making it the world’s longest predator?
120 Feet
.
