All cnidarian species are capable of
sexual reproduction
, which occurs in only one phase of the life cycle, usually the medusa. Many cnidarians also reproduce asexually, which may occur in both phases.
Where does fertilization occur in cnidaria?
Many species are also able to reproduce sexually by releasing sperm and eggs into
the water column
during mass spawning events. Fertilization takes place within the water column, and larva then attach to the ocean floor to complete their development.
Do cnidarians have internal or external fertilization?
Another variable in the sexual reproduction of cnidarians is whether
fertilization takes place internally or externally
. In some species, sperm released by the males must be ingested by the females in order to reach eggs within the female body for fertilization.
Is internal fertilization or external fertilization?
| Internal fertilization External fertilization | Offsprings have a high chance of survival. Offsprings have low chances of survival. | For example: cow, dog, humans, etc. For example: fish, frog, etc. |
|---|
Why Coelenterates are called cnidarians?
Coelenterates are called Cnidarians
because they contain specialized cells called cnidoblasts
. They possess stinging structures called nematocysts.
What are 5 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 is fertilisation inside the body of a female called?
Internal fertilization
is the union of an egg cell with a sperm during sexual reproduction inside the female body.
Is fertilization internal or external in Mollusca?
Introduction to Mollusca and the Class Gastropoda
A generic mollusc is dioecious with paired gonads. Eggs or sperm are released into the coelomic cavity and carried outside by ducts.
Fertilization is external
and the zygote develops into a gastrula and then a free-swimming trochophore larva.
What is the movement 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.
Which is an example of external fertilization?
Descriptive external fertilisation examples are that of
salmon, trout fish and codfish
. Both the female and male release their eggs and sperms respectively into the water where they diffuse and fertilize. In the list of external fertilization examples, aquatic animals such as mammals and sharks are exceptions.
Is external fertilization asexual?
In
asexual reproduction
, an individual can reproduce without involvement with another individual of that species. … During sexual reproduction, the male gamete (sperm) may be placed inside the female’s body for internal fertilization, or the sperm and eggs may be released into the environment for external fertilization.
What are the disadvantages of internal fertilization?
Harder to bring both male and female into intimate contact. Limited amount of offspring being produced at any given time. Higher risk of sexually transmitted diseases being passed on
.
Why Cnidaria are so called?
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
.
Do coelenterates have mesoderm?
Since coelenterates
possess only body cavity and no development of mesoderm
in germ layer and no true internal coelom, they are not considered coelomates in which well differentiated organs can be accommodated.
Is coelom present in Coelenterata?
All coelenterates are aquatic, mostly marine. The bodyform is radially symmetrical, diploblastic and
does not have a coelom
. The body has a single opening, the hypostome, surrounded by sensory tentacles equipped with either nematocysts or colloblasts to capture mostly planktonic prey.
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.
