Echinoderms
What happens when sea cucumbers are threatened
they may expel their internal organs; then, these organs regenerate in a few weeks
what are their tube feet used for then
to move particles of food into their mouth
What are tube feet
hollow, thin-walled tubes that each end in a suction cup; as the pressure in the tube feet changes, the animal is able to move along by pushing out and pulling in its tube feet
Do Echinoderms have a head or brain
No
What are soft-bodied echinoderms that have a leathery covering and tentacles around their mouth and rows of tube fee on their upper and lower surfaces
sea cucumbers
What are disk or globe-shaped animals covered with spines
sea urchins, sea biscuits and sand dollars
How do sea stars reproduce
sexually when females release eggs and males release sperm into the water
what does Echinoderm mean
Spiny skin (echinos-spiny; derma-skin)
sea urchins
have sacs near the end of the spines that contain toxic fluid that is injected into predators; spines also help in movement and burrowing
How does the brittle star grow new parts
regeneration
How do sea stars repair themselves
regeneration-grows a new limb if it loses one
Whats the largest group of echinoderms
sea stars
Other groups include what
1. Brittle stars 2. sea urchins 3. Sand dollars 4. Sea cucumbers
Characteristics of these
1. Hard endoskeleton 2. covered by a thin, bumpy or spiny epidermis 3. Radially symmetrical-allows them to sense food, predators and other things in their environment from all directions
What three things do all echinoderms have
1. Mouth 2. Stomach 3. Intestines
What echinoderm has fragile, slender, branched arms that break off easily
The brittle star
how do brittle stars move
Using their flexible arms-NOT tube feet
what do sea urchins feed on
algae
Why are brittle stars called that
because their arms break off so easily if they are grabbed by a predator
Other echinoderms feed on what
dead and decaying materical called detritus
what do sea cucumbers eat
detritus and plankton
Why are echinoderms of value
1. they feed on dead organism and help recycle material 2. sea urchins control the growth of algae 3. sea urchin eggs and sea cucumbers are used for food i some places 4. they are used for research and may be sources of medication 5. sea stars control populations of other animals
how far do echinoderms date back
400 million years ago
How many species of echinoderms exist
6,000
what do they have though
A nerve ring that surrounds the mouth; also cells that respond to light and touch
why are they so important
Echinoderms more closely resemble animals with backbones than any other group of invertebrates, since they have complex body systems and an embryo that develops the same way that the embryos of animals with backbones develop
What characteristic is unique to Echinoderms
Have a water-vascular system that allows them to move, exchange carbon dioxide and oxygen, capture food, and release wastes
Describe sand dollars
Have no arms, but have a 5-pointed pattern on their surface
How many of the 6,000 are sea stars
More than 1/3
What type of echinoderm has at least five arms arranged around a central point and their arms are lined with thousands of tube feet?
Sea stars
What is the water-vascular system
a network of water-filled canals with thousands of tube feet connected to it
sand dollars
are covered with stiff, hairlike spinds
what do sea stars feed on
worms and mollusks