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Clade Radiata Flashcards

0
Q

Phylum Cnidaria?

A

Nettle like
Characterized by cnidocytes (contains specialized stinging organelles)
Mostly marine
Ancient group- longest fossil history of all metazoa
Traditionally 4 classes but 5th proposed

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1
Q

Class Radiata?

A

Sponges are asymmetrical and do not have true tissues
True tissues characterize the clade eumetazoa
Phylum Cnidaria and Ctenophora are basal members of clade eumetazoa
Exhibit radial symmetry and are diploblastic but only have tissue level organization (no organs)

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2
Q

Who are the Cnidaria?

A

Mostly in warm shallow marine habitats
Efficient predators
Sometimes symbiotic relationships
Many sessile but others can move slowly

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3
Q

Cnidarian form?

A

Many exhibit polymorphism
Polyp: sessile
Medusa: floating or free swimming
Both have similar structure

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4
Q

Body wall?

A

Surronds gastrovascular cavity

Outer epidermal layer, inner gastrodermal layer, mesogleal layer in between

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5
Q

Mesoglea?

A

Gelatinous jelly like

Can contain fibres, ameboid, epitheliomuscular cells

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6
Q

Gastrodermis?

A

Epithelial cells lining gastrovascular cavity
Can contain nutritive muscular, interstitial and gland cells as well as cnidocytes, gonads
Very weak muscle layer so water in cavity serves as hydrostatic skeleton

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7
Q

Epidermis?

A

Outer layer containing various cells

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8
Q

Epitheliomuscular?

A

Covering and contractions

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9
Q

Interstitial?

A

Undifferentiated stem cells

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10
Q

Gland?

A

Secrete mucus

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11
Q

Cnidocytes?

A

Contain cnidae, abundant on tentacles

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12
Q

Sensory?

A

Flagellum as receptor, join with nerve cells

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13
Q

Nerve?

A

Multi or bipolar

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14
Q

Cnidae?

A

Tiny capsules within cnidocytes
Capsules covered with operculum
Contain coiled thread
Has tiny barbs in most common form (nematocysts)

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15
Q

Why have cnidae?

A

3 diff functional types

Penetrants, volvents, glutinants

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16
Q

Penetrants?

A

Penetrate prey and inject venom

17
Q

Volvents?

A

Recoil and entangle prey

18
Q

Glutinants?

A

Secrete adhesive

19
Q

How do cnidae work?

A

Most equipped with modified Cilium acting as a trigger (cnidocyl)
Others sensitive to vibrations
Discharge under enormous hydrostatic pressure

20
Q

Nerve net?

A

No central nervous system
Diffuse nervous network comprised of two connected nerve nets
Can be considered a neural muscular system in conjugation with sensory and epitheliomuscular cells

21
Q

Feeding and digestion?

A

Mouth opens into gastrovascular cavity
Gland cells secrete enzymes and initiate extracellular digestion
Nutritive muscular cells phagocytize particles
Undigested particles carried by ameboid cells back to gastrovascular cavity for expulsion

22
Q

Locomotion for cnidaria?

A

Colonial polyps are permanently attached
Hydros and see anamones can glide via mucus secretions using pedal discs
Also measuring worm movement
Medusae swim by contracting the bell

23
Q

Reproduction?

A

Polyps and medusae play diff roles
Polyps can make other polyps via asexual reproduction
Clones via budding or fission
Clones can be dispersed or can stay attached to form a colony that may exhibit division of labor

24
More on reproduction?
Polyps in classes Hydrozoa and Scyphozoa eventually make medusae asexually Medusae are dioecious (male or female individuals) Produce gametes and reproduce sexually to form a free swimming zygote larva (planula)
25
Polyps or medusae?
Sea anemones and corals are all polyps (both have sexual and asexual reproduction tho) True jellyfish are only medusae Hydrozoa can alternate forms
26
Class Hydrozoa?
Life cycle alternates bw polyp and medusae Lack tentacles for feeding Most are marine and colonial Hydras are an exception
27
Feeding of Hydrozoa?
Feeding response cuz of glutathione Released by prey, wounded by nematocysts Usually asexual budding
28
Hydroids?
``` Typical members of class Hydrozoa Have a medusa stage in life cycle ```
29
More on Hydrozoa
Have base, stalk, and 1 or more terminal polyps (zooids) Most polyps are feeding forms (hydranths or gastrozooids) Some have forms for defence (dactylozooids) Newly budded individuals do not detach but add to the colony
30
Medusae form?
From buds of gonangiae Usually leave colony as free swimming larva (planula) Hydroid medusae typically small
31
Class Scyphozoa?
Most of the larger jellyfishes ->predominately Medusas Many are bioluminescent No velum on bell but often have a scalloped margin Gonads in gastric pouches->internal fertilization, ciliated planula larva attaches and develops into a scyphistoma to make more polyps or a strobila that becomes medusa
32
Class staurozoa?
Solitary stalked polyp Polyp top resembles a medusa Sexual reproduction
33
Class Cubozoa?
Predominant medusa Bell shape, almost square with tentacles at each corner Tentacle base as a tough blade (pedalium) Rhopalia each have six eyes Umbrella margin not scalloped and turns inwards to form the velarium (like a velum)
34
Deadliness of Cubozoa?
Most deadly cnidocytes to humans found in tropical seas One member, the sea wasp (chironex fleckeri) is claimed to be most venomous marine animal known Horribly painful Most humans die after getting stung, specially if they are swimming Lions mane: also painful+fatal stings. Toxins appear to be species specific.
35
Class Anthozoa?
``` Occur only as polyps Coral and sea anemones Found in diverse marine environments Solitary or colonial Many supported by skeleton Divided into three subclasses: zoantharia, octocorallia and who cares ```
36
Subclass zoantharia?
Sea anemones Cylindrical with crown of tentacles surrounding an oral disc and pharynx Cavity as 6 chambers Aconite also contain nematocysts Also contain zoantharian corals Stony corals Tiny anemones living in secreted calcareous cups No pedal disc but skeletal cup~also hexamerous Large sheet over time
37
Subclass octocorallia?
Soft and horned corals Cavity as 8 chambers->8 feather like tentacles around oral disc Almost all are colonial and communicate through gastrodermal tubes (solenia). Very important ecosystems. Habitat and nursery for many fish Reef building takes dissolved calcium and carbonate ions and precipitate it to form reefs.
38
Where cnidaria live?
Shallow waters Warm waters Clear waters with little or no nutrients (zooxanthelle need light for photosynthesis).
39
Phylum Ctenophora?
Comb jellies 8 rows of comb-like plates (ctenes) used for locomotion Can bioluminese Can have adhesive cells (colloblasts) but do not make nematocysts Also predators like Cnidaria All are monoecious
40
Ctenophora medusa or polyp?
Support for idea that anthozoan life was ancestral Medusoid form added later New grouping maybe (medusozoa?)

Zoology (5 decks)

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