Cnidaria is a phylum that consists of over 10,000 known species of animals found in aquatic and marine environments. Cnadrians reproduce both sexually and asexually, using polyps and medusae, which are two forms of cnadria. Polyps and medusae reproduce asexually by budding, but also take part in sexual reproduction for some cnadrians.
What animals belong to the Cnidaria phylum?
Phylum Cnidaria include jellyfish, sea anemones, and sponges. These classes share basic phylum Cnidaria traits. Cnidaria are multicellular. They are also invertebrates. Invertebrates are animals with no backbone. Most Cnidarians are marine animals. Cnidarians have radial symmetry. Unlike phylum Porifera they have body tissues. However, they lack organs.
What animals live in cnidarians?
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. The phylum Cnidaria is made up of four classes: Hydrozoa (hydrozoans); Scyphozoa (scyphozoans); Anthozoa ...
How do cnidarians reproduce asexually?
Special reproduction cycle in some Cnidarians:
- Their reproduction is different; they do not possess a body system for reproduction.
- Sexual reproduction- The sperms that are produced by the male organisms swim freely in the water and fertilize with the eggs that are located in the mouth or the stomach ...
- Asexual reproduction- The polyps after getting attached may form colonies. ...
What are facts about the phylum cnidarian?
Cnidaria Facts. Depending on the situation, cnidarians can live for about a few days to 4000 years. Most of the organisms that belong to this phylum cnidaria do not contain eyes and not even any developed organ.
How do cnidarians reproduce asexually?
Reproduction of Cnidarians In general, polyps primarily reproduce asexually by budding, however, some produce gametes (eggs and sperm) and reproduce sexually. Medusae usually reproduce sexually using eggs and sperm.
Which cnidarian form reproduces asexually?
PolypsCnidarian Reproduction Polyps usually reproduce asexually. One type of asexual reproduction in polyps leads to the formation of new medusae. Medusae usually re produce s exually. Sexual reproduction forms a zygote.
Do cnidarians lay eggs?
In the adult, or medusa, stage of a jellyfish, they can reproduce sexually by releasing sperm and eggs into the water, forming a planula.
Are sexes separate in Cnidaria?
Cnidarians display various sexual systems, from hermaphrodism (simultaneous or sequential) to gonochorism, and sexual reproduction can take place at different stages, polyp or medusae [6].
What are the characteristics of phylum Cnidaria?
Cnidarians exhibit a specific characteristic – tentacles with stinging nematocytes which serve as small harpoons which react to stimuli by giving out tiny stinging cells which can poison and hook potential prey. Cnidarians do not show bones and a central nervous system, rather have a nerve net.
What organisms are asexual?
What are some examples of asexual reproduction? Organisms like hydra, paramecium, starfish, planaria, and mint plants reproduce by asexual reproduction. The reproduction of these organisms does not involve the fusion of male and female gametes.
Can jellyfish feel pain?
Can jellyfish feel pain? Jellyfish don't feel pain in the same way that humans would. They do not possess a brain, heart, bones or a respiratory system. They are 95% water and contain only a basic network of neurons that allow them to sense their environment.
Does jellyfish have gender?
Jellyfish are usually either male or female (with occasional hermaphrodites). In most cases, adults release sperm and eggs into the surrounding water, where the unprotected eggs are fertilized and develop into larvae.
What type of reproduction does a cnidarian have?
One type of asexual reproduction by polyps leads to the formation of new medusae. Cnidarians switch from the polyp to the medusa stage by a form of asexual reproduction in which the polyp develops a stack of medusoid structures that can then bud off to become independent medusae.
What is the life cycle of a cnidarian?
A generalized life cycle of a cnidarian. Medusae primarily reproduce by sexual reproduction with the formation of a larval stage called the planula.
How do polyps reproduce?
In general, polyps primarily reproduce asexually by budding, however, some produce gametes (eggs and sperm) and reproduce sexually. Medusae usually reproduce sexually using eggs and sperm. Depending on the species, cnidarians can be monoecious (also called hermaphroditic), with individuals capable of producing both eggs and sperm, ...
What is the process of a polyp forming a medusae?
Polyps forming medusae: strobilation. The process of strobilation is when a polyp asexually reproduces to form medusae. The cartoons labeled 1 through 3 depict a polyp developing the medusae. The cartoons labeled 4 through 6 show the continued development of the medusa once it is released from the polyp.
Do sperm and eggs go into the water?
In other species, both sperm and eggs are released into the aquatic environment by the organisms, and fertilization takes place externally.
What is the cnidaria?
Cnidaria is a phylum present under the kingdom Animalia that contains over 11,000 species of aquatic animals that are found both in freshwater and marine environments. Their distinguishing feature is cnidocytes, these are specialized cells that they use primarily for capturing prey. Their bodies consist of a non-living jelly-like substance called mesoglea, which is sandwiched between two layers of epithelium that are mostly one cell thick.
How do cnidaria spawn?
Spawning is usually driven by environmental conditions like changes within the water temperature, and their release is triggered by lighting conditions such as sunrise, sunset or the phase of the moon. Many species of Cnidaria may spawn simultaneously within the same location. There are too many ova and sperm for predators to eat quite a small percentage. One of the famous examples is the Great coral reef, where a minimum of 110 corals and a couple of non-cnidarian invertebrates have produced enough gametes to make the water cloudy. These mass spawnings may produce a hybrid. In some species, the ova releases the chemicals that attract the sperm of an equivalent species.
What phylum are cnidarians in?
Cnidarians formerly belonged to Ctenophores under the phylum Coelenterata, but increasing awareness of their differences caused them to be placed in separate phyla. Many scleractinian corals which form the structural foundation for coral reefs possess polyps that are filled with symbiotic photosynthetic zooxanthellae. While reef-forming corals are almost entirely restricted to warm and shallow marine waters, other cnidarians are often found at great depths, in polar regions, and in freshwater.
How do anthozoa use their digestive system?
Some Anthozoa has ciliated grooves on their tentacles that allow them to pump water out of and into the digestive cavity without opening the mouth. This improves the process of respiration after feeding and the animals which use the cavity as a hydrostatic skeleton, in order to regulate the water pressure within the cavity without expelling undigested food. The animals produce large quantities of antioxidants to neutralize the surplus oxygen.
What kingdom is Cnidaria in?
Cnidaria belongs to the kingdom Animalia and phylum Coelenterata. It is classified into three main groups:
How does a cnidarian amphimixis grow?
This grows normally, on the other hand, these organisms absorb their tentacles and split them horizontally into a series of disks that become juvenile medusae, through a process called strobilation. The juveniles swim off and slowly grow to maturity, while the polyp re-grows and should continue strobilation periodically. The adults have gonads that are found within the gastrodermis, and these are involved in the release of ova and sperm into the water within the breeding season. This phenomenon of succession is organized differently among generations is sometimes called "alternation of asexual and sexual phases" or it is also known as "metagenesis". But these alteration processes should not be confused with the alternation of generations as found in plants as both of them are different in nature.
Why does Chironex expand?
In the case of Chironex, chemical changes in the cnida's contents may cause them to expand rapidly by polymerization.
How many species of cnidaria are there?
Cnidaria is a phylum that consists of over 10,000 known species of animals found in aquatic and marine environments. Cnadrians reproduce both sexually and asexually, using polyps and medusae, which are two forms of cnadria.
What is the process of a jellyfish becoming a polyp?
One example of this is in jelly fish. A larva swims around until it finds a good site, and then becomes a polyp. It then undergoes a process called Storbilation, where the polyp absorbs tentacles and splits horizontally into a series of disks that become juvenile medusae. The juveniles swim off, and slowly mature.
Why do animals spawn?
Spawning is when the eggs and sperm of an aquatic animal are released in water. It is caused by environmental factors such as changes in water temperature. Females release ova into the water, and males release sperm to fertilize the eggs.
Do juvenile gonads release sperm?
The juvenile forms into an adult and develops gonads in gastroderm. The gonads then release ova and sperm into the water during breeding season.
Which two major forms are observed in the Cnidarian lifecycle?
Medusa which are the sexual form and polyps which are the asexual forms are the two major forms observed in the Cnidarian lifecycle.
What are polyps in a cnidarian?
The polyps may occur in groups in some cnidarian species. They are referred to as colonies and sometimes their coelenteron cavity is shared between the members of the colony.
What is the role of the planula in the formation of zygotes?
The planula attaches to the substratum like the sea bed and develops into a polyp.
What are polyps in coral called?
Some colonies include the ‘Hydroids’ which are the hydrozoan colonies, anthozoan soft corals, and hard corals.
How does asexual reproduction work?
Asexual reproduction- It can be through budding, binary fission, or pedal laceration in which the pedal discs which are broken into small pieces regenerate to form the anemones.
What are the skeletons of coral used for?
The skeletons of the corals are used to produce cement. They vary in hue and the pink, purple, and other hues of these corals are incorporated in jewels. The sea fans’ and sea whips’ core are bent to produce bracelets and beads.
What is the function of a nematocyst?
The nematocysts act as a stinger that can be used to defend them and to attack their prey. They consist of a touch-sensitive hair-like projection, a coiled stinger, and a barb. When it comes in contact with the prey, it propels and releases its barb and the coiled stinger comes out and attacks the prey. The barb may have the poison. They can harm human beings too.
How do cnidarians reproduce?
These organisms are called simultaneous hermaphrodites and release gametes into the ocean in egg-sperm bundles. Some species are also either male or female and produce either eggs or sperm. Fertilization (the uniting of egg and sperm) can happen externally in the water column, but can also happen internally. Many coral species reproduce externally in a process called broadcast spawning (Fig. 3.30 B). These species tend to have synchronous spawning events in which all individuals in the colony or area release their gametes at the same time. This is often triggered by environmental cues like full moons, temperature, or chemical signals from other individuals. Broadcast spawning increases the likelihood of sperm and egg from the same species meeting and for genetic mixing to take place. In other cnidarians the male releases sperm into the water, but fertilization happens inside the body when sperm from a male colony enters the female and fertilizes eggs internally. This type of sexual reproduction is called brooding, resulting in the release of a fully formed larva (Fig. 3.30 C).
What are the cnidarians?
The phylum Cnidaria (pronounced “nih DARE ee uh”) includes soft-bodied stinging animals such as corals, sea anemones, and jellyfish (Fig. 3.23 A). The phylum’s name is derived from the Greek root word cnid - meaning nettle, a stinging plant. Cnidarians are found in many aquatic environments. Sea anemones are widely distributed, from cold arctic waters to the equator, from shallow tide pools to the bottom of the deep ocean. Jellyfish float near the surface of the open oceans and in some tropical freshwater lakes. Corals are found primarily in shallow tropical waters, but a few grow in deep cold ocean waters. Small anemone-like cnidarians like Hydra sp. are also found in freshwater lakes and streams. Cnidarians range in size from tiny animals no bigger than a pinhead to graceful giants with trailing tentacles several meters long.
How do jellyfish move?
Many jellyfish are supported by an umbrella shaped structure that is composed of a modified layer of mesoglea. When a ring of muscles contracts, a jet of water is forced out from under the umbrella, moving the jellyfish forward. When the muscles relax, the stiff mesoglea springs back to its original shape, and the umbrella opens again (Fig. 3.29). Alternating muscle contraction and relaxation creates pulsating movements that propel the jellyfish through the water. Even so, jellyfish are such poor swimmers that they are considered plankton. Plankton are aquatic organisms that cannot swim against a current.
How do cnidarians respond to stimuli?
To respond to stimuli, cnidarians use a rudimentary muscular system consisting of muscle cells lying in bands up and down the body wall and in a circle around the mouth cavity ( Fig. 3.27). The body shortens when the vertical bands contract. If muscles on only one side contract, the body bends in that direction. The mouth closes when the circular muscle contracts.
What are some examples of animals that look similar to cnidarians?
Some animals that look similar to cnidarians are actually not part of the same phylum. An example of this is a type of jelly called a ctenophore (Fig. 3.23 B). Ctenophores were removed from the phylum Cnidaria and placed in a new phylum called Ctenophora (pronounced ti-NOF-or-uh). Although both ctenophores and cnidarians have similar bodies with thin tissue layers enclosing a middle layer of jellylike material, scientists now group them separately. These comb rows, called ctenes ( ctene meaning comb) is how the ctenophores get their common name of comb jellies.
What phylum are moon jellies in?
Fig. 3.23. ( A) Moon jellies ( Aurelia aurita) from the phylum Cnidaria
Do jellyfish sting?
All cnidarians are carnivorous predators. Jellyfish capture small drifting animals with their stinging cnidocyte-filled tentacles. Even the sessile coral polyps and sea anemones are predators ready to sting prey, grasp it in their tentacles, and push it into their mouth. The potency of the stinging venom varies among species. Some cnidarian venoms have little effect on humans. Others are extremely toxic. The venom of the Portuguese man-of-war ( Physalia physalis) is potent enough to inflict a painful sting, even after it is washed up on the beach.
How do cnidarians reproduce?
Cnidarians can reproduce asexually by budding (another organism grows off the main organism, such as in anemones), or sexually, in which spawning occurs. Male and female organisms release sperm and eggs into the water column, and free-swimming larvae are produced.
What is the phylum of cnidaria?
The Cnidaria ( Cnidaria spp.) is the phylum of animals that contains corals, jellyfish (sea jellies), sea anemones, sea pens, and hydrozoans. Cnidarian species are found throughout the world and are quite diverse, but they share many similar characteristics.
How big is a cnidaria?
The smallest Cnidaria is the Hydra, which measures under 3/4 of an inch; the largest is the lion's mane jellyfish which has a bell that can measure more than 6.5 feet in diameter; including its tentacles. it can exceed 250 feet long. Dania Chesham/Getty Images.
What are the two types of cnidarians?
There are two types of cnidarians, called polypoid and medusoid. Polypoid cnidarians have tentacles and a mouth that face up (think of an anemone or coral). These animals are attached to a substrate or colony of other animals. Medusoid types are those like jellyfish—the "body" or bell is on top and tentacles and mouth hang down.
How do cnidarians interact with humans?
There are many ways cnidarians may interact with humans: They may be sought-after in recreational activities, such as scuba divers going to reefs to look at corals. Swimmers and divers may also need to beware of certain cnidarians because of their powerful stings. Not all cnidarians have stings that are painful to humans, but some do, and some may even be fatal. Some cnidarians, such as jellyfish, are even eaten. Different cnidarian species may also be collected for trade for aquariums and jewelry.
What are the two layers of cells in a cnidarian?
Two Layers of Cells: Cnidarians have an epidermis, or outer layer, and a gastrodermis (also called the endodermis), which lines the gut. Separating the two layers is a jelly-like substance called the mesoglea, which is most visually apparent in jellyfish. Digestive Cavity (The Coelenteron): The coelenteron contains their stomach, gullet, ...
What is the scientific name of the cnidaria?
Scientific Name: Cinadaria. Jennifer Kennedy, M.S., is an environmental educator specializing in marine life. She serves as the executive director of the Blue Ocean Society for Marine Conservation. The Cnidaria ( Cnidaria spp.) is the phylum of animals that contains corals, jellyfish (sea jellies), sea anemones, sea pens, and hydrozoans.
