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How would you describe the subclass Hexacorallia?

Hexacorallia is a class of Anthozoa comprising approximately 4,300 species of aquatic organisms formed of polyps, generally with 6-fold symmetry. It includes all of the stony corals, most of which are colonial and reef-forming, as well as all sea anemones, and zoanthids, arranged within five extant orders.

Why does the anemone belong in the Cnidaria phylum?

Sea anemones are ocean-dwelling members of the phylum Cnidaria. They are invertebrates belonging to the class of Anthozoa. The name Cnidaria (with a silent ‘c’) refers to the cnidae, or nematocysts, that is, the cellular entity of the venom apparatus, which all Cnidarians possess.

Why are corals cnidarians?

Cnidarians are soft-bodied animals that include corals, jellyfish, and sea anemones. These soft-bodied animals have saclike digestive cavities and tentacles containing rows or stinging cells used for defense and capture of food.

How do the anthozoa differ from other animals within the Cnidaria?

Anthozoa is included within the phylum Cnidaria, which also includes the jellyfish, box jellies and parasitic Myxozoa and Polypodiozoa. Unlike other members of this phylum, anthozoans do not have a medusa stage in their development. Instead, they release sperm and eggs into the water.

Are cnidarians dangerous to humans in any way?

All cnidarians have the potential to affect human physiology owing to the toxicity of their nematocysts. Most are not harmful to humans, but some can impart a painful sting—such as Physalia, the Portuguese man-of-war, and sea anemones of the genus Actinodendron.

How do cnidarians benefit humans?

Cnidarians like some edible species of jellyfish are suitable for human consumption and are used as a source of food and as an ingredient in various dishes. These are cultured and harvested on a large scale to serve as a source of food for millions. Sea Anemones are also a very famous delicacy.

Do comb jellies have stinging cells?

The most notable is that instead of tentacles armed with stinging cells, comb jellies have sticky cells called colloblasts that do not sting and eight rows of cilia, or combs, that propel them through the water and produce a flickering rainbow-like appearance with their movements.

What happens when a human gets stung by a cnidarian?

Unfortunately, many divers are all too familiar with the stinging cells of many cnidarians. Even slight contact with many species can produce painful stings that result in burning welts. They eventually blister and are slow to heal.

How do cnidarians defend themselves?

Cnidarians defend themselves and catch prey using their tentacles, which have cells called cnidocytes at their tips.

Do cnidarians have a nervous system?

Cnidarians are considered “nerve net animals” even though their nervous systems include various forms of condensation and centralization. Yet, their broad, two-dimensional muscle sheets are innervated by diffuse nerve nets.

How does food get into a cnidarian?

Food enters through the mouth and waste products exit through the mouth, and in between, things pass through a part of the cnidarian’s body called the gastrovascular cavity. Food is digested by the cells found inside the gastrovascular cavity, both through cellular digestion and through the use of digestive enzymes.

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 type of food do cnidarians eat?

Most cnidarians prey on organisms ranging in size from plankton to animals several times larger than themselves, but many obtain much of their nutrition from dinoflagellates, and a few are parasites. Many are preyed on by other animals including starfish, sea slugs, fish, turtles, and even other cnidarians.

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.

Where do cnidarians usually eliminate their food wastes?

Cnidarians respire and eliminate the wastes of cellular metabolism by diffusion through their body walls. Cnidarians gather info from their sensory cells.

What is the difference between sponges and cnidarians?

These organisms show a simple organization. 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.

How do cnidarians get oxygen?

Cnidarians are aquatic animals that contain stinging cells called cnidocytes. While cnidarians do not have lungs or other respiratory organs, they do use body cells to take in oxygen and expel waste gases. This can be a problem in areas with stagnant water, as the lack of circulation decreases the available oxygen.