Dictionary » P » Polyp



noun, plural: polyps

(1) (zoology) The hollow, columnar, sessile form of Cnidarians (as opposed to the medusa form)

(2) (pathology) An abnormal (usually benign) pedunculated growth, protruding from a mucous membrane


(zoology) Cnidarians take two body forms: polyp and medusa. The polyp body form is sessile, elongated, and hollow. Their lower end is attached to a substratum. Their free upper end is where the mouth and the tentacles are located. One of the major differences between polyp and medusa is their mode of reproduction. Polyps generally reproduce asexually (by budding) whereas medusae, by sexual reproduction. Some Cnidarians take a polyp body form (e.g. sea anemones and corals); others, medusa (e.g. scyphozoans). But there are also Cnidarians that exhibit both polyp and medusa stages in their life cycle (e.g. most hydrozoans).

Word origin: Greek polupous, from polus (many) + pous (foot)


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Re: Respiration of a polyp (hydra)

Hydra are diploblastic, i.e. they have only two cell layers. Respiration is by simple diffusion.

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by Gavin
Fri Oct 28, 2011 1:19 am
Forum: Zoology Discussion
Topic: Respiration of a polyp (hydra)
Replies: 1
Views: 2434

Respiration of a polyp (hydra)

How does a polyp respire? Couldn't find any answer in the internet...

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by tillL
Thu Oct 27, 2011 3:34 pm
Forum: Zoology Discussion
Topic: Respiration of a polyp (hydra)
Replies: 1
Views: 2434

Re: animal with the longest lifespan

... this immortal being so small hehe : Turritopsis nutricula or immortal jellyfish is a hydrozoan whose medusa, or jellyfish, form can revert to the polyp stage after becoming sexually mature. It is the only known case of a metazoan capable of reverting completely to a sexually immature, colonial ...

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by master94
Mon Jul 12, 2010 12:25 pm
Forum: Zoology Discussion
Topic: animal with the longest lifespan
Replies: 9
Views: 13840

Why Cnidaria swim?

... this is one of them: What is "The use" of a swimming stadium among Cnidaria (and also swamps) ? I think the answear is that becouse of a polyp- colony is single- sexual, they have to produse medusa, if they want to get some kind of gentic variation. Am i getting this right, or can somone ...

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by ManBearPig89
Wed Mar 24, 2010 2:47 pm
Forum: Zoology Discussion
Topic: Why Cnidaria swim?
Replies: 4
Views: 3641

Stomach bloating and weight gain

What was the size of the polyp, >10mm ? If so I would wonder why this did not raise concerns with the doctors. Although I think this is unrelated to any change in body size, It might cause the severe pains which prompted you to visit ...

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by MichaelXY
Sun Apr 26, 2009 9:23 am
Forum: Physiology
Topic: Stomach bloating and weight gain
Replies: 453
Views: 2917423
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