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3A Zoology - Invertebrates > The Colourful Lives of Early Aquatic Inverts > Flashcards

The Colourful Lives of Early Aquatic Inverts Flashcards

1
Q

What are the phylum porifera?

A

Sponges

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2
Q

What is the porifera feeding mechanism?

A

Filter feeders

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3
Q

Do porifera move?

A

No, they are sessile

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4
Q

Porifera have totipotent cells, what does this mean?

A

Can change form and function

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5
Q

What division of animals are porifera (based off tissues)?

A

Metazoans, although without well defined tissues and organs. Used to be considered parazoans (no true tissues)

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6
Q

What is the unique cell of cnidarians and what does it do?

A

Cnidocyte with nematocysts - stings

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7
Q

Do cnidarians move?

A

Either sessile or slow-moving

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8
Q

What are the 4 main Porifera cell types?

A

Pinacocytes, archaeocytes, choanocytes, porocytes

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9
Q

What are pinocyte cells?

A

Form the external epithelium of porifera, can contract to regulate water flow

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10
Q

What are choanocytes?

A

Flagellated filter feeding cells of porifera.

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11
Q

Explain the filter feeding mechanism of porifera.

A

Collar of microvilli on choanocytes trap food particles from water. Flagella keep a constant current through the water. Food encapsulated in main cell body then passed to Archaeocytes for digestion

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12
Q

What are archeocytes?

A

Porifera digestive cells that move in the mesohyl. Are totipotent.

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13
Q

What 3 cell types can archaeocytes differentiate into?

A

Sclerocytes, spongocytes, collencytes

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14
Q

What are porocytes?

A

Porifera tubular cells that form pores in simple sponge types (Asconoids).

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15
Q

What are the three body plans of Porifera, from simplest to most complex.

A

Asconoid, Syconoid, Leuconoid

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16
Q

What is the major difference between porifera and protista?

A

Porifera - multicellular
Protista - unicellular

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17
Q

What are the advantages of increased body size and complexity in porifera vs protista?

A

Efficient filter feeding, increased surface area for gas exchange (cellular respiration), better defence (spicules irritate predator mouthparts), structural support (spicules and spongin fibres)

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18
Q

Describe the evolutionary pressures giving rise to polymorphism in Cnidaria. (long answer)

A

Adaptation to different environment - specialised morphs depending on habitat and benthic/pelagic.
Optimized feeding - gastrozooids are feeding polyps with tentacles and cnidocytes for capturing prey.
Reproduction - gonozooids specialised for reproduction and do not typically engage in feeding activities.
Dactylozooids - specialised defence polyps equipped with nematocysts, protection from predators and environmental threats. Indirectly contributes to reproductive success and colony growth/longevity.
Division of labour allows colony to efficiently allocate resources and energy between feeding, reproduction and defence.

19
Q

How are cnidarians dimorphic?

A

Two forms - polyp or medusa

20
Q

What are the 3 polymorphic forms of polyps?

A

Gastrozooids, gonozooids and dactylozooids

21
Q

What kind of symmetry do medusa forms of cnidaria show?

A

Tetramerous - divided in units of 4

22
Q

Which form of Cnidaria is free swimming and which is sessile?

A

Free swimming = medusa
Sessile = polyp

23
Q

What are the reasons for radial symmetry in Cnidaria? (long answer)

A
  • Primitive body plan without cephalisation
  • Allows prey capture in all directions, especially beneficial due to sessile or slow-moving nature
  • Radial arrangement of sensory structures allows stimuli detection from multiple directions, allowing rapid responses to wave current, presence of prey and predators
  • Defence from predators in all directions
  • Release gametes and larvae in multiple directions, increasing likelihood of successful reproduction
  • Benefical for benthic and pelagic Cnidarians. Benthic - extend tentacles in all directions while remaining sessile. Pelagic (e.g. jellyfish) - essential for propulsion
24
Q

Photosynthesis

Energy
Calcification
Stress
Bleaching

Describe the importance of symbiotic algae (zooxanthellae) to coral biology. (long answer)

A
  • Symbiodinium algae provides nutrients through photosynthesis. The products of photosynthesis, such as glucose and oxygen, are released into the coral tissue, providing essential nutrients and oxygen for coral metabolism.
  • Zooxanthellae can make up as much as 30% of the total tissue in coral polyps and as much as 90% of their energy frequently comes from the symbionts.
  • This allows them to allocate resources towards calcification—the process by which corals build their calcium carbonate skeletons. This enables corals to grow and maintain their structural integrity, contributing to the formation of reef structures.
  • Symbiotic algae contribute to the heat tolerance of corals by dissipating excess light energy as heat during periods of high temperature stress, thereby reducing the risk of coral bleaching. Zooxanthellae can be ejected, leading to coral bleaching under high stress which starves corals and polyps die.
25
Q

What kind of algae provide nutrients to corals?

A

Symbiodinium algae

26
Q

Where are zooxanthellae found in corals?

A

Inside cells

27
Q

What percentage of energy comes from symbionts of corals?

A

90%

28
Q

What type of vore are cnidaria (what do they eat)?

A

Carnivore

29
Q

How do Cnidaria feed?

A

Feeding tentacles capture prey using cnidocytes which eject nematocysts to kill or immobilize prey. Prey is brought towards the mouth, small particles are transported along the tentacles via cilia. Prey are ingested whole and waste material is expelled through the mouth.

30
Q

What are the three main categories of cnidocytes?

A

Nematocysts, spirocysts and ptychocysts

31
Q

What Cnidarians have spirocyst cnidocytes?

A

Anthozoa, such as sea anemones

32
Q

What do spirocysts do?

A

They are adhesive, used to catch prey. Used alongside nematocysts to hold prey in place and kill/eat them.

33
Q

What do ptychocysts do?

A

Discharge from ptychocysts can have various effects. It may entangle or ensnare predators, deter them from attacking, or immobilize prey for capture and consumption

34
Q

What are cnidocytes?

A

Unique cells found only in cnidarians that contain nematocysts. Triggered by mechanical stimulation of the cnidocil, which when inverted causes the nematocyst to be injected into prey very quickly, killing or immobilizing it. Also used in defence against predators.

35
Q

Describe a typical Cnidaria life-cycle

A
  1. eggs, sperm released
  2. larva forms
  3. larva settle on hard surface
  4. larva mature to polyps
  5. polyps elongate and bud off many young jellyfish
  6. young jellyfish mature
36
Q

Cnidaria have a diploblastic body plan. Describe this concept.

A

Organisms with a diploblastic body plan have two well-defined germ layers: the ectoderm and the endoderm. The ectoderm forms the epidermis (outer skin) and the endoderm forms the gastrodermis (inner lining of digestive cavity). A gelatinous matrix called mesoglea fills are between layers.

37
Q

What animal phylum body plan shows no symmetry?

A

Porifera

38
Q

What animal phyla body plans show radial symmetry?

A

Cnidaria and echinodermata

39
Q

What is the symmetry of the body plan of the majority of animals?

A

Bilateral

40
Q

What animals are anthozoa?

A

Sea anemones, stony and soft corals and sea pens.

41
Q

What is unique about the cnidocyte trigger mechanism of anthozoa?

A

More advanced and can be tuned to capture prey more efficiently, such as having spirocysts (adhesive)

42
Q

What animals are cubazoa?

A

Box jellyfish

43
Q

What animals are scyphozoa?

A

‘True’ jellyfish

44
Q

What are the 4 well known classes of Cnidaria?

A

Hydrozoa, scyphozoa, cubozoa and anthozoa

3A Zoology - Invertebrates (12 decks)

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