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AK - marine > Echinodermata 1 > Flashcards

Echinodermata 1 Flashcards

1
Q

Introduction

Key characteristics

Body structure

Feeding

Reproduction
Larvae

A

…

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2
Q

Introduction

6 points

A
  1. Isolated and distinct taxa [very different to the other phyla we’ve looked at]
  2. ~7,000 extant species
  3. Almost exclusively marine [havent developed adaptations to live terrestrially or freshwater]
  4. Global distribution
  5. Benthic, occur at all depths
  6. Often keystone species [very important roles as keystone species]
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3
Q

Classification

A

Kingdom: Metazoa

Phylum: Echinodermata

Class: 6 classes

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4
Q

Key characteristics

10 points

A
  1. Calcareous, mesodermally derived endoskeleton
  2. Radially symmetrical
    Pentamerous (5 rays/ sides [moving out from central disc])
    Oral/aboral axis [mouth is on underside, against sediment surface]]
  3. Embryogeny deuterostomous (mouth second) [mouth opens second. Blastopore forms anus not the mouth]
    Blastopore typically forms the anus not the mouth
  4. Triploblastic (ectoderm, mesoderm and endoderm)
  5. Tissues, organs, circulatory system and non-centralised nervous system [no definitive head for brain to develop. Series of nerve nets and other adaptations]
  6. No excretory organs [across body wall]
  7. Coelomic water vascular system
  8. Complete through gut but anus sometimes absent
  9. Dioecious, some hermaphroditism
  10. Bilaterally symmetrical larvae
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5
Q

Body structure

5 points

A
  1. Body wall;
    cuticle, monolayered epidermis, thick connective dermis, muscular layer and peritoneum.
  2. Trimeric coelomic compartments
    Protocoel (part of the haemal system)
    mesocoel (WV system [water vascular])
    metacoel (bulk of body)
  3. Dermal ossicles
    Rigidity and protection

May or may not be covered by epidermis

  1. Mutable collagenous tissues
    Connective tissue between ossicles and body wall

Can be rigid or soft depending on requirement [at any given time. Can maintain positions for long times. Not using energy]

Important for locomotion

Saves energy when in unusual postures

  1. Papulae
    Outpockets of body wall
    Gas exchange
    Extend or retract
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6
Q

Calcareous Endoskeleton

4 points

A
  1. Mesodermally derived endoskeleton [skeleton under a layer of tissue]
  2. Calcium carbonate crystals in the form of calcite [how endoskeleton formed]
  3. Porous ossicles and plates
    Attached together by muscle and connective tissue

Flat plates, spines, rods and crosses [form various structures. Different species have different ossicles. Key feature for identifying species]

  1. Pedicellariae
    Jaw shaped [appendages found on surface]

[uses]
Cleaning
Defence
Feeding

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7
Q

Water vascular system

8 points

A
  1. Varies between classes
  2. Madreporite [mostly on surface of body]
    Permits water to enter system

Perforated with hydropores [sits around ring]

  1. Stone, ring and radial [into arms] canals
  2. Tiedemann’s body and Polian vesicles [on rind canal]

Blind pounces [contain fluid, believed to regulate pressure within water vascular system. Maintain pressure very important for movement]

Regulate internal pressure

  1. Tube feet and ampullae
  2. Fluid is moved around by cilia [within the system]
  3. Circulatory and locomotary function [important for]
  4. Linked to hemal system
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8
Q

Tube Feet

5 points

A
  1. Structure
    Ampulla
    Podium
  2. Locomotion
    Muscles force water into tube feet which extend and retract.
    Suckers present depending on class.
  3. Respiration and excretion of waste though thin body wall [important for]
    Exchange of oxygen and carbon dioxide
    Release of nitrogenous waste
  4. Feeding
  5. Sensory
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9
Q

Feeding

6 points

A
  1. Suspension feeders (Crinoidea, Asteroidea, Ophiuroidea, Echinoidea, Holothuroidea)
2. Predators (Asteroidea, Ophiuroidea)
Eversible stomach
Secrete digestive enzymes
“Suck” up partially digested prey
Pisaster ochraceus feeds on closed mussels [can feed on it whilst its still in shell. Muscle becomes weaker and opens and can suck it out]
  1. Scavengers (Asteroidea, Ophiuroidea)
  2. Deposit feeders (Ophiuroidea, Holothuroidea, Asteroidea)
    Surface and subsurface [e.g. bury themselves into sediment and consume at same time]
  3. Detritivores (Echinoidea)
  4. Herbivores (Echinoidea)
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10
Q

Sexual Reproduction

5 points

A
  1. Dioceous
  2. External and internal fertilisation
  3. Indirect or direct development [of larvae]
  4. Egg brooding
  5. Hermaphrodites
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11
Q

Asexual reproduction

2 points

A
  1. Fissiparity

Break-up of disc [regrow into 2 separate indiciduals again

Regrowth appendages

  1. Regeneration
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12
Q

Larval development

2 points

A
  1. Planktotrophic
    Larvae feed in plankton

Eggs small with limited energy

  1. Lecithotrophic

Larvae feed on yolk

Large eggs with high energy content

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AK - marine (15 decks)

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