How do Hydromedusae differ from Scyphomedusae?
Hydromedusae are smaller and more delicate than scyphomedusae or cubomedusae; they may be completely absent from the life cycle of some hydrozoan species. Some other species produce medusae, but the medusae never separate themselves from the polyps. Cubozoans have medusae commonly known as box jellyfish,…
What is dimorphism in Cnidaria?
Some cnidarians are dimorphic, that is, they exhibit both body plans during their life cycle. In these species, the polyp serves as the asexual phase, while the medusa serves as the sexual stage and produces gametes.
What are the 2 body plans of cnidarians?
Cnidarians have two body forms—polyp and medusa—which often occur within the life cycle of a single cnidarian. Sea nettle (Chrysaora fuscescens). The body of a medusa, commonly called a jellyfish, usually has the shape of a bell or an umbrella, with tentacles hanging downward at the margin.
On what structure are the stinging cells of cnidarians located?
Whereas the defining cell type for the sponges is the choanocyte, the defining cell type for the cnidarians is the cnidocyte, or stinging cell. These cells are located around the mouth and on the tentacles, and serve to capture prey or repel predators.
Are Scyphozoa polyp or medusa?
MEDUSA is dominant in Scyphozoans, but polyp stage is also present at some point during their life cycle.
Why is Scyphozoa called jellyfish?
Scyphozoan Medusa is called True Jellyfish because they have a cup-shaped medusa, which is different from the cube-shaped medusae of box jellyfish.
What are Zooids in Cnidaria?
Zooids are the individual polyps present in the colonies of hydroids. Individual zooids in the colony perform various different tasks such as reproductive polyps are called gonozooids, feeding individuals are called gastrozooids.
What are medusa and 11 polyps?
Sessile structures are called polyps while the swimming forms are called medusa. The key difference between polyp and medusa is that polyp is a fixed, cylindrical structure, representing the asexual stage and medusa is a free swimming, umbrella-like structure, representing the sexual stage.
What are the stinging cells of cnidarians called?
Cnidocytes, also known as stinging cells, are specialized neural cells that typify the phylum Cnidaria (sea anemones, corals, hydroids, and jellyfish) [1,2,3]. These cells contain an organelle called cnida or cnidocyst, which is the product of extensive Golgi secretions.
Are jellyfish male or female?
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 is the function of polyp?
Anatomically simple organisms, much of the polyp’s body is taken up by a stomach filled with digestive filaments. Open at only one end, the polyp takes in food and expels waste through its mouth. A ring of tentacles surrounding the mouth aids in capturing food, expelling waste and clearing away debris.
What is polyp form?
polyp, in zoology, one of two principal body forms occurring in members of the animal phylum Cnidaria. The polyp may be solitary, as in the sea anemone, or colonial, as in coral, and is sessile (attached to a surface).
How do zooids form?
Zooid Budding All bryozoan zooids produce new zooids by budding. In Phylactolaemata, buds arise from a specific site on the mid-ventral wall of the parental zooid. With every new bud comes the appearance of new bud primordia, which may or may not develop further.
What do zooids look like?
Each zooid consists of a tubular body that has two layers separated by a thin jellylike mesoglea (layer of connective tissue), a terminal mouth, and surrounding circlet(s) of tentacles. The zooids are joined basally to a common living tube called the stolon…
Why do jellyfish sting cells?
It is important to note that stinging cells can be found on all parts of a jellyfish, not just the tentacles! Stinging cells help jellyfish catch prey because they contain organelles called nematocysts.
Is a jellyfish a medusa or polyp?
Throughout their lifecycle, jellyfish take on two different body forms: medusa and polyps. Polyps can reproduce asexually by budding, while medusae spawn eggs and sperm to reproduce sexually. Learn more about the lifecycle and reproduction of jellyfish.
Is a hydra a medusa or polyp?
Hydra is a sessile and cylindrical polyp form.