intro to echinoderms · 2018-02-15 · intro to echinoderms p1, 5 . phylum echinodermata •means...
TRANSCRIPT
INTRO TO
ECHINODERMS P1, 5
Phylum Echinodermata
• Means “spiny skinned”
• Members called echinoderms
5 Main Classes
• Asteroidea sea stars
• Echinoidea sea urchins & sand dollars
• Ophiuroidea brittle stars
• Crinoidea sea lilies & feather stars
• Holothuroidea sea cucumbers
Key Characteristics
• Lack segmentation no
cephalothorax or abdomen
• Radial symmetry (usu. 5-part)
• Has central point of body
• All similar structures regularly
arranged around it
• Internal skeleton called
endoskeleton
SEA STARS P1, 5
Sea Star Anatomy
Jonathan Bird’s Blue World – Sea Stars
• https://www.youtube.com/watch?v=vxbW4W_nM
Zs
• Please write in your notes:
• Northern Sea star
• Basket star
• Crown-of-thorns sea star
• Giant Pacific sun star
• Blue Linckia sea star
• For each sea star, jot down the behavior/life
activity described by Jonathan Bird
Adaptations in the Sea Star
Survival & Protection
• Often lose an arm in struggles can regenerate
• Spiny covering provides support & protection
Respiration & Circulation
• Breathe t/ skin & tube feet
• Skin gills on dorsal side, tube feet on ventral side
• O2 diffuses into fluid-filled space called coelom
• Ciliated cells circulate oxygenated fluid around body
• Open circulatory system
Adaptations in the Sea Star (cont’d)
Feeding & Locomotion
• Use tube feet for movement & food-getting
• Suction disks cling to surfaces
• Feed primarily on bivalves • Pull on shells in opposite direction w/ tube feet
• Adductor muscles get tired & bivalve opens
• Push stomach into shell & digest prey externally w/ enzymes
• Water vascular system allows for locomotion • Sieve plate stone canal ring canal radial canals tube
feet
• Ampullae of tube feet contracts tube feet extends
• Tube feet contracts water forced back into ampullae creates suction
Adaptations in the Sea Star (cont’d)
Reproduction & Regeneration
• Separate sexes, but must examine internally to
identify
• Gonads located in each arm near central disk
• Sperm & eggs shed into water
• External fertilization, external development
• Asexual reproduction t/ regeneration
• If arm torn off, whole new sea star can grow from
severed arm if part of central disk is present
Zombie Sea Stars video
• https://www.youtube.com/watch?v=KrfcglOmBYw
SEA URCHINS & SAND
DOLLARS P1, 5
Sea Urchins
• Class Echinoidea
• Movable spines attached
to endoskeleton
• Use spines & tube feet to
move
• Endoskeleton formed by
fused bony plates (CaCO3)
• Inhabit intertidal & subtidal
zones along rocky coasts
• Scrape algae off rocks w/
five-toothed mouth
structure called Aristotle’s
lantern
Long-spined sea urchin
Purple & green sea urchin
Rock-boring urchin
Life Cycle of the Sea Urchin
• Male & female can’t tell gender
externally
• External fertilization, external
development
• Larvae part of plankton
community until settle on seafloor
Army of Sea Urchins
• https://www.youtube.com/watch?v=D3W4OCnHyCs
Sand Dollars & Sea Biscuits
• Sand dollars have short spines covering skin
• Use to burrow in sand
• Feed by catching plankton & organic debris in sticky strings beneath spines
• Flat endoskeleton (CaCO3) remains often collected by people
• Sea biscuits are more rounded w/ longer spines
• Inhabits sandy seafloors around coral reefs
• Eats organic debris & algae
BRITTLE STARS P1, 5
Brittle Stars
• Class Ophiuroidea
• Most abundant of echinoderms
• Nocturnal, bottom-dwelling animals hide under rock during day
• Live in intertidal zone (arctic to tropics)
• Subgroup called basket stars • Live on deep ocean floor
• Distinct flattened central disk
Locomotion & Food-Getting
• Do NOT use tube feet
for movement have
muscles in arms
• Multiple feeding
methods:
• Use arms to gather
organic debris
• Capture live
invertebrates
• Filter-feed using sticky
strands
• Capture suspended food
bits w/ tube feet
SEA LILIES & FEATHER
STARS P1, 5
Sea Lilies & Feather Stars
• Class Crinoidea
• Members called crinoids
• Most ancient group of echinoderms
• Body composed of dozens of feathery
arms perched atop jointed stalk
• Generally limited ability to move
• Sea lilies sessile
• Feather stars crawl along coral reefs &
swim by flapping arms
• Filter feed by waving arms & capturing
zooplankton w/ tube feet
• Also do NOT use tube feet for
locomotion
Feather Star Videos
Feather Star Swimming
https://www.youtube.com/watch?v=rRej1VKDgcE
Feather Star Feeding
https://www.youtube.com/watch?v=3mz0jNyHkJ0
Sea Urchin Consumes Feather Star
https://www.youtube.com/watch?v=LNbT-VhoWXs
SEA CUCUMBERS P1, 5
Sea Cucumbers
• Class Holothuroidea
• Soft, oblong body lacks
arms, but has tube feet
arranged in 5 rows
• Lost endoskeleton & spines
only small bony pieces
in skin
• Live on sandy & rocky
seafloors in intertidal &
subtidal zones
• Most abundant at great
depths
Life Activities
• Use sticky, branching tentacles (modified tube feet) to trap
microscopic organisms
• Located around mouth
• Can extend & retract
• 5 rows of tube feet help it move slowly & trap food
particles in sand
• One-way digestive tract
• Breathe t/ anus
• Water goes in gas exchange occurs inside coelom across
membranes of respiratory tree
• Can release digestive organs when disturbed
• Predator eats decoy later regenerates lost organs
Sea Cucumber Videos
Sea Cucumber Fights With Guts
https://www.youtube.com/watch?v=wXf_YodWw40
Most Extreme
https://www.youtube.com/watch?v=vsLBOkYLLeI
Pearlfish Hides Inside a Sea Cucumber
https://www.youtube.com/watch?v=giA16BoH_no