Phylum Cnidaria Flashcards

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Questions and Answers

Cnidaria are ______ (diplo or triploblastic)?

diploblastic

All Protostomes and Deuterostomes are _____ (diplo or triploblastic)?

triploblastic

Are cnidarians more organized than sponges?

True

Are cnidarians more sessile or motile?

False Signup and view all the answers

What do cnidarians feed on?

able to kill and eat prey more highly organized, swift, and intelligent than themselves Signup and view all the answers

What makes cnidarians good predators?

possess tentacles that bristle with nematocytes Signup and view all the answers

What are characteristics of the phylum Cnidaria?

<ol> <li>cnidocytes house nematocytes 2. aquatic 3. radial symmetry 4. two types of individuals: polyps and medusae 5. diploblastic 6. medoglea present 7. incomplete gut (gastrovascular cavity) 8. tentacles around mouth 9. asexual and sexual reproduction 10. muscular contraction vs. epitheliomuscular cells 11. no excretory or respiratory systems 12. no coelomic cavity</li> </ol> Signup and view all the answers

What is the stinging organelle?

nematocytes Signup and view all the answers

When a nematocyte is fired, its stimulus can achieve a velocity of _ and an acceleration of __.

2 meters/sec. and 40,000x gravity Signup and view all the answers

Nematocytes inject ____ into prey, easily immobilizing prey.

toxins Signup and view all the answers

There are over ____ species in phylum Cnidaria. It is made up of _ and _____.

9,000; hydroids, sea anemones and jellyfish Signup and view all the answers

What is the trigger that creates osmotic pressure to effect a coil for nematocytes in cnidocytes?

cnidocil Signup and view all the answers

Cnidarians have the longest fossil history with specimens from over _______ years ago.

700 million Signup and view all the answers

Are cnidarians more widespread in marine or freshwater? What region are they in?

marine, mostly found in shallow water in warm tropical regions Signup and view all the answers

What are some examples of mutualistic relationships between cnidarians and other creatures?

<ol> <li>Hydroids and sea anemones can live on snail shells inhabited by hermit crabs to provide protection 2. Ctenophores, molluscs, and flatworms eat hydroids and use the stinging nematocytes for their own defense 3. clownfish and sea anemones</li> </ol> Signup and view all the answers

What are the four traditional classes of Cnidaria?

Hydrozoa, Scyphozoa, Cubozoa, Anthozoa Signup and view all the answers

Which class is made up of hydroids, fire corals, Portuguese man-of-war?

Hydrozoa Signup and view all the answers

What is the largest class; including stony and soft corals, sea anemones?

Anthozoa Signup and view all the answers

What class is made up of cube or box jellyfishes?

Cubozoa Signup and view all the answers

What class is made up of true jellyfishes?

Scyphozoa Signup and view all the answers

What is the fifth class of Cnidaria? What is special about it?

Staurozoa - no medusa in life cycle but has polyp topped by medusa-like region Signup and view all the answers

What is the word for when two different types of life forms can be presented in an organism?

dimorphic body plan Signup and view all the answers

What are the two forms cnidaria can be in?

Polyp (hydroid) form - adapted to sedentary or sessile life; Medusa - free-living and floating Signup and view all the answers

What is the more appropriate name for jellyfish now?

sea jelly Signup and view all the answers

Which retains sac-like body plans? Polyps or Medusa?

False Signup and view all the answers

Medusa is essentially unattached polyp with tubular body widened and flattened into a _____ shape.

bell Signup and view all the answers

The polyp form has the tubular body with the mouth facing and surrounded by .

upward; tentacles Signup and view all the answers

In the polyp form, the mouth leads to the _.

gastrovascular cavity Signup and view all the answers

In the polyp form, the aboral end is connected to ____ by _ ___.

substratum; pedal disk Signup and view all the answers

How do polyps reproduce asexually?

budding, pedal laceration, fission Signup and view all the answers

If polyp detaches from origin, it becomes a _____.

clone Signup and view all the answers

If the bud remains attached to the polyp that made it, it becomes ____.

colony with shared gastrovascular cavity Signup and view all the answers

What is the form of cnidarians in medusa form?

bell/umbrella shaped and exhibit tetramerous symmetry Signup and view all the answers

Study Notes

Characteristics of Phylum Cnidaria

Cnidarians are diploblastic organisms with two cell layers.
More organized than sponges, showing advanced morphological structure.
Primarily sessile; some species can move.

Feeding and Predation

Cnidarians are effective predators, able to kill and consume prey more complex than themselves.
Their tentacles, equipped with nematocytes, aid in capturing prey.

Key Features of Cnidarians

Possess cnidocytes that contain nematocytes, the stinging organelles.
Exhibit radial symmetry and can exist as polyps or medusae.
Lack excretory or respiratory systems and coelomic cavities.
Have an incomplete digestive system, characterized by a gastrovascular cavity.

Nematocyte Functionality

When triggered, nematocytes can achieve a velocity of 2 meters/sec and an acceleration of 40,000 times gravity.
Inject toxins into prey, immobilizing them for consumption.

Diversity and Habitat

Over 9,000 species exist in this phylum, including hydroids, sea anemones, and jellyfish.
Cnidarians thrive in marine environments, particularly in warm tropical waters.

Relationships and Interactions

Examples of mutualism include clownfish residing in sea anemones, hydroids on hermit crab shells, and defense mechanisms among various marine creatures.

Taxonomy of Cnidaria

Four traditional classes: Hydrozoa, Scyphozoa, Cubozoa, Anthozoa.
Hydrozoa includes hydroids and Portuguese man-of-war.
Anthozoa encompasses stony and soft corals as well as sea anemones.
Cubozoa represents box jellyfish, while Scyphozoa includes true jellyfish.
Staurozoa is unique for lacking a medusa stage in its life cycle.

Body Plans and Forms

Cnidarians exhibit a dimorphic body plan, existing as polyps or medusae.
Polyp form is sedentary, while medusa is free-floating with a bell shape.
Both forms retain sac-like body structures.

Reproductive Strategies

Polyps reproduce asexually through budding, pedal laceration, or fission.
Detached polyps develop into clones, while attached buds form colonies sharing a gastrovascular cavity.

Morphological Features

The polyp has an upward-facing mouth surrounded by tentacles and connects to the substratum via a pedal disk.
The medusa form is bell-shaped with a tetramerous symmetry.

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Description

Test your knowledge on Phylum Cnidaria, including sea anemones and jellyfish, with these flashcards. Each card presents a key concept related to cnidarians, such as their tissue organization and mobility. Perfect for biology students or anyone interested in marine life.