Phylum Echinodermata Flashcards

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0
Q

Sea urchins & sand dollars

A
  • long solid plates around internal organs
  • sand $ burrow for protection
  • sea urchins protected by spines
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1
Q

7 characteristics

A
  • 5-part radial symmetry
  • internal skeleton
  • water vascular system
  • tube feet
  • marine
  • complete digestive tract
  • coelomates
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2
Q

Sea stars

A
  • creep slowly on ocean floor
  • mostly carnivorous (prey on bivalves)
  • can regenerate body parts (if central disc is included)
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3
Q

Brittle stars

A
  • slender, flexible arms
  • move rapidly to escape predators
  • can shed arms when attacked
  • can regenerate
  • nocturnal
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4
Q

Sea lillies and feather stars

A
  • aka crinoids (ancient class)

- perch on reefs & capture plankton with tube feet

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5
Q

Sea cucumber

A
  • detritus feeders (suck organic matter)

- 5 rows of tube feet along body display radial symmetry

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6
Q

Movement

A
  • sand $ and sea urchins have protective spines on their fused exoskeletons
  • sea stars and brittle stars have flexible arm joints
  • sea cucumber has plates reduced to ossicles/spicules in body wall
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7
Q

Describe how water vascular system aids movement

A
  • water enters through maldreporite
  • goes through stone canal
  • enters ring canal
  • enters radial canals
  • enters tube feet
  • muscles pull tube feet upwards and suction cup pressure is created
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8
Q

Respiration

A
  • diffusion across thin tube feet tissue (lots of surface area)
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9
Q

Feeding

A
  • herbivores (sea urchin) use 5-part jaw-like structure to scrape algae from rocks
  • carnivores (sea star, brittle star) pry apart bivalve shell externally & absorbs partially digested food
  • scavengers (sea cukes) vacuums ocean floor taking in sand & detritus
  • filter-feeders (sea lillies) wave tube feet to capture floating phytoplankton
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10
Q

Reproduction

A
  • most are separate sexes
  • external fertilization
  • bilateral free-swimming larvae
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11
Q

Internal circulation

A
  • nutrients and wastes removed from body by water vascular system
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12
Q

Excretion

A
  • feces removed through anus

- ammonia/nitrogen wastes diffuse through water vascular system & tube feet

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13
Q

Response to environment

A
  • no head
  • poorly developed nervous system
  • has nerve ring around mouth & radial nerves
  • scattered sensory cells to detect light, gravity, etc.
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14
Q

Pedicillaria

A

Pincher like structure that keeps surface of organism free of debris

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15
Q

Ampulla

A

Bulb-like sac on tube feet that squeezes to control amount of water

16
Q

Ambulacral groove

A

Trench along oral surface of sea stars arms- holds tube feet