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
Q

More on reproduction?

A

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
Q

Polyps or medusae?

A

Sea anemones and corals are all polyps (both have sexual and asexual reproduction tho)
True jellyfish are only medusae
Hydrozoa can alternate forms

26
Q

Class Hydrozoa?

A

Life cycle alternates bw polyp and medusae
Lack tentacles for feeding
Most are marine and colonial
Hydras are an exception

27
Q

Feeding of Hydrozoa?

A

Feeding response cuz of glutathione
Released by prey, wounded by nematocysts
Usually asexual budding

28
Q

Hydroids?

A
Typical members of class Hydrozoa 
Have a medusa stage in life cycle
29
Q

More on Hydrozoa

A

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
Q

Medusae form?

A

From buds of gonangiae
Usually leave colony as free swimming larva (planula)
Hydroid medusae typically small

31
Q

Class Scyphozoa?

A

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
Q

Class staurozoa?

A

Solitary stalked polyp
Polyp top resembles a medusa
Sexual reproduction

33
Q

Class Cubozoa?

A

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
Q

Deadliness of Cubozoa?

A

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
Q

Class Anthozoa?

A
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
Q

Subclass zoantharia?

A

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
Q

Subclass octocorallia?

A

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
Q

Where cnidaria live?

A

Shallow waters
Warm waters
Clear waters with little or no nutrients (zooxanthelle need light for photosynthesis).

39
Q

Phylum Ctenophora?

A

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
Q

Ctenophora medusa or polyp?

A

Support for idea that anthozoan life was ancestral
Medusoid form added later
New grouping maybe (medusozoa?)