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planula, plural planulae, free-swimming or crawling larval type common in many species of the phylum Cnidaria (e.g., jellyfish, corals, and sea anemones). The planula body is more or less cylindrical or egg-shaped and bears numerous cilia (tiny hairlike projections), which are used for locomotion.
- How do planula larvae move?
- How does a cnidarian move?
- How do polyps move?
- How does adult hydra attach to feed?
- What does a planula become?
- Do all invertebrates have planula larva?
- Are Cnidaria motile?
- How do cnidarians move quizlet?
- Do cnidarian polyps move?
- What is the function of the polyp?
- What is polip?
- How do hydras move?
- What does hydra use for movement?
- How does hydra use the Nematocyst?
How do planula larvae move?
They soon hatch, and free-swimming "planula" larvae emerge from the female's mouth or brood pouch and set out on their own. A planula is a tiny oval structure the outer layer of which is lined with minute hairs called cilia, which beat together to propel the larva through the water.
How does a cnidarian move?
They contract their hollow, saucer-shaped bodies (called bells) to force water out, which propels them forward. Their long. tentacle-like arms, which trail out behind them, are used to sting and capture prey.
How do polyps move?
However, most do so weakly and are carried passively by currents over long distances. Polyps are generally sedentary. Pennatulacean colonies move slowly across soft substrata by action of their inflatable peduncle (a stalk that attaches to the strata in the lower end and to the polyp body on the higher end).
How does adult hydra attach to feed?
Feeding. Hydra mainly feed on aquatic invertebrates such as Daphnia and Cyclops. While feeding, Hydra extend their body to maximum length and then slowly extend their tentacles. ... Upon contact, nematocysts on the tentacle fire into the prey, and the tentacle itself coils around the prey.
What does a planula become?
The planula metamorphoses into a sessile (i.e. fixed-position), usually benthic (i.e. bottom dwelling) polyp called a 'scyphistoma' and it is the scyphistoma, still attached to the surface on which the planula settled, that produces a new free-swimming medusa.
Do all invertebrates have planula larva?
Many invertebrates (e.g., cnidarians) have a simple ciliated larva called a planula. Flukes have several larval stages, and annelids, mollusks, and crustaceans have various larval forms.
Are Cnidaria motile?
Medusa forms are motile, with the mouth and tentacles hanging down from an umbrella-shaped bell. Cnidarian morphology: Cnidarians have two distinct body plans, the medusa (a) and the polyp (b). ... Some cnidarians are polymorphic, having two body plans during their life cycle.
How do cnidarians move quizlet?
How do cnidarians move? Since Cnidarians do not have a mesoderm, they do not have any true muscle. They move by epithelial muscular cells (cells in the epidermis that can contract and are made up myosin and actin.
Do cnidarian polyps move?
Some sessile polyps can move too, very small distances. Here's a hydra showing off its gymnastic skills. Some cnidarians live in colonies. These colonies are made of polyps called zooids.
What is the function of the polyp?
Polyps extend their tentacles, particularly at night, containing coiled stinging nettle-like cells or nematocysts which pierce and poison and firmly hold living prey paralysing or killing them.
What is polip?
A polyp is a projecting growth of tissue from a surface in the body, usually a mucous membrane. Polyps can develop in the: colon and rectum. ear canal. cervix.
How do hydras move?
The hydras usually move by looping and somersaulting, by attaching the tentacle ends and pulling themselves along. When there is an insufficient supply of oxygen, hydras move to regions of higher oxygen content.
What does hydra use for movement?
Walking movement - This type of movement involves the use of tentacles. Here, the Hydra uses its tentacles as legs to move from one point to another. Gliding - Hydra can also move through gliding on a surface.
How does hydra use the Nematocyst?
Nematocysts are produced by nematoblasts, or cnidoblasts, and are used for capturing and paralyzing prey or for defense. ... Each nematocyst contains a coiled, hollow thread that can have barbs or spines and often contains poison.
