echinoderms are __________, ________, __________, ________, ____________, _____________ and...
TRANSCRIPT
•There are ______ characteristics of echinoderms.
•All echinoderms have:• Spiny skin• An internal skeleton (endoskeleton)• Five-part radial symmetry• A water vascular system• Tube feet
They live in the ocean!
* All echinoderms have __________. Some of them have small hair-like spines, like the starfish.
* Some echinoderms have long spines, like the sea urchin.
* The water vascular system also helps an echinoderm _____.
* An echinoderm’s water vascular system is _________________________________.
* The system opens to the outside through the sieve like madreporite.
Madreporite •Opening to the outside
•Connects to a ring canal around the mouth
•5 radial canal extend up the arms from the ring canal
* Echinoderms have __________.
* An echinoderm’s tube feet are used for _________________________________.
*Five-part radial symmetry.
* But the bodies are 2-sided. Mouth side is the oral surface & the opposite side is the aboral surface.
*They have no anterior or posterior end and lack ______________.
Plan for the Day
•Review unifying characteristics of Echinoderms
•Examine 5 classes of the Phylum Echinodermata
•Check your understanding activity
•* Mollusc & Echinoderm test - WEDNESDAY
* Carnivores: use tube feet to move
and to open bivalves to eat
* A sea star is able to re-grow its arms
Class Echinoidea
Sea urchins & sand dollars* Have solid plates surrounding their
internal organs
*Most are detritivores or grazers.
* Sea urchins have a mouth hidden under its body and they eat sea algae (kelp).
* A sea urchin is not very active. Sometimes, it does move slowly using its __________. When not moving it uses its feet to stick to the ocean floor.
* Sea urchins have longer and sharper ________ that they use to protect themselves.
Class Ophiuroidea
Brittle Stars
* Have slim, flexible arms, and can move quickly. Can detach an arm if being attacked!* Filter feeders and detritivores that come out at night
Class Holothuroidea
Sea cucumbers
* Feed on detritus
* Can expel all their internal organs as a decoy if being attacked!
Class CrinoideaSea
lilies & feather stars
* Oldest echinoderms
* Filter feeders: attach to the seafloor by a stock and use their tube feet to catch prey
Echinoderms: Form & Function
Feeding
Respiration
Circulation
Excretion
Response
Movement
Reproduction
FeedingSea urchins: five-part jaw to eat algae
Sea stars: tube-feet to pry open mollusks shells. Evert their stomach into the mollusk shell and secretes digestive enzymes. Brings stomach and digested food back inside. (digests externally)
Sea cucumbers: eat sand & detritus on the ocean floor or filter feed
Sea lilies: tube-feet to trap plankton
Respiration & Circulation**Water vascular system** - primary system
•Carries oxygen, food and wastes*Tube-feet allow some diffusion through thin walls for respiration (gas exchange)
*Skin gills are present in some echinoderms for gas exchange
*Sea cucumber: pumps water in and out of its anus to provide oxygen to its respiratory trees
Excretion
Nitrogen-containing wastes are excreted through thin-walled tube feet
Digestive wastes (feces) are released through the anus
ResponsePrimitive nervous
system (no brain)
Nerve ring surrounding the mouth connects to radial nerves to the body segmentsSenses: to detect light, gravity and chemicals
Movement
Tube feet ! – All use tube feet to move (water-vascular system) - hydraulics
Sea stars & brittle stars move arms because of flexible joints
Sand dollars & sea urchins move their spines
Sea cucumbers move using muscular wall & tube feet
ReproductionExternal fertilization
•Eggs produced in ovaries & sperm produced in testes
•Gametes released into the water for fertilization
•Larvae are free swimming
Echinoderm EcologyUrchin Barren: created by
overpopulation of urchins
Sea stars are predators and help control the growth of mollusks (mussels) & corals
Echinoderm EcologyThreat to coral reefs: sea star
called crown-of-thorns
Feeds on coral and has destroyed coral reefs in Australia