Cnidarians are distinguished from all other animals by
having cnidocytes that fire harpoon like structures and are usually used mainly to capture prey
. In some species, cnidocytes can also be used as anchors.
Are cnidarians invertebrates?
Cnidarians are
aquatic invertebrates
. They have tissues and radial symmetry. They also have tentacles with stingers. There are two cnidarian body plans: the polyp and the medusa.
Why are cnidarians invertebrates?
A cnidarian (ny-DAIR-ee-uhn) is a simple invertebrate (an animal without a backbone) that
lives in the water and has a digestive cavity with only one opening
. Jellyfish, sea anemones, corals, and hydra are all cnidarians.
How are cnidarians classified?
Cnidarians are classified into four main groups:
non-moving
(sessile) Anthozoa (sea anemones, corals, sea pens); Cubozoa (box jellies);swimming Scyphozoa (jellyfish); and Hydrozoa, a broad group that includes all the freshwater cnidarians as well as many marine forms. … Cnidaria have no organs like hearts or lungs.
What are defining characteristics of Cnidaria?
Phylum Cnidaria includes animals that
exhibit radial or biradial symmetry and are diploblastic
, meaning that they develop from two embryonic layers, ectoderm and endoderm. Nearly all (about 99 percent) cnidarians are marine species.
Is a jellyfish a mollusc?
question_answer Answers(2)
Ans:
Phylum mollusca
include soft bodied animals with hard shell Eg: snails, octopus, mussels, oysters. Phylum Coelenterata contain special structure called coelenteron where the food digested.It include jelly fish and sea anemones.
Are cnidarians Coelomate animals?
Cnidarians are not considered to have a coelom
because they are diploblastic, so they don’t have any mesodermic tissue. Cnidaria are a phylum consisting of aquatic animals like jellyfish, anemones, and corals. Cnidaria have cnidocytes, specialized stinging cells.
Why are sponges not considered Eumetazoans?
A sponge consists of many specialized cells that can act and change jobs freely of each other and are not controlled by an overall center so not tissue. The lack of organization means
the sponge cannot act on any stimulus as a whole
.
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.
Are cnidarians radial or bilateral?
The
bilateral
symmetry of Cnidaria is thought to be inherited from the common ancestors of both cnidarians and triploblastic bilaterians. The secondary radial symmetry of Cnidaria evidently is a result of the adaptation to the sessile mode of life.
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 3 structures do all cnidarians possess?
In addition to a primitive digestive cavity, cnidarians have a
decentralized nervous system, muscle tissue, reproductive tissues, and a hydrostatic skeleton
. A hydrostatic skeleton is maintained by the internal pressure of fluids within the organism.
What do all cnidarians have in common?
All Cnidaria are aquatic, mostly marine, organisms. They all have
tentacles with stinging cells called nematocysts
that they use to capture food. Cnidarians only have two body layers, the ectoderm and endoderm, separated by a jelly-like layer called the mesoglea. Most Cnidarians have radial symmetry.
Is jellyfish a Coelenterate?
Coelenterates (Phylum Coelenterata or Cnidaria) include
jellyfish
, anemones, corals, and hydras. The phylum is characterized by a gelatinous body, tentacles, and stinging cells called nemadocysts. Most species are found in marine waters, but some occur in brackish or even fresh water.
What are the five characteristics of cnidarians?
- Radially Symmetrical.
- Body multicellular, few tissues, some organelles.
- Body contains an internal cavity and a mouth.
- Two different forms exist, medusa and polyp.
- Reproduction is asexual or sexual.
- Has a simple net like nervous system.
- Has a distinct larval stage which is planktonic.
What are 3 characteristics that all cnidarians have in common?
What are three characteristics that all cnidarian have in common? Cnidarians have
an epidermis, gastrodermis, mesoglea, gastrovascular activity and tentacles
. Also, they have cnidocytes and a nervous system composed of diffuse web of interconnected nerve cells called a nerve net.
