Download Chapter 29: Echinoderms and Invertebrate Chordates

Chapter 29: Echinoderms and Invertebrate Chordates
Section 1: Echinoderms
Echinoderms

Includes starfish, sea urchins, sand dollars, etc.

Belong to the phylum ______________________________________
o Stretches back to the beginning of the Cambrian Period, more than
______________________________________________________
What Is an Echinoderm?

__________________________________ are spiny skinned animals

In addition to having a spiny skin, echinoderms are characterized by
________________________________________________________, an
___________________________________________, a ____________________
_________________________________________, and suction-cuplike
structures called ____________________________

The internal skeleton, or ________________________________, is made up of
hardened plates of calcium carbonate, which are often bumpy or spiny

The __________________________________________ consists of an internal
network of fluid-filled canals connected to external appendages called
_____________________________
o Water vascular system is involved in many essential life functions in
echinoderms
Form and Function in Echinoderms

Adult echinoderms have a body plan with five parts organized symmetrically
around a ________________________

Typically have neither an anterior nor a posterior end and no brain

The side where the mouth is located is called the __________________________,
and the opposite side is called the ______________________________________

The water vascular system opens to the outside through a sieve like structure
called the ____________________________

The entire water vascular system operates like a series of living hydraulic pumps
that can propel water in or out of the tube feet

The tube feet act like living suction cups

All echinoderms ____________________ with their tube feet, and some use their
tube feet for feeding
Feeding

_________________________
o Use their tube feet to pry open the shells of bivalve mollusks such as
clams and scallops
o Once opened, the carnivores flips its ________________________ out of
its ___________________, pours out _______________________, and
digests its prey in the prey’s own shell

__________________________
o Scrape algae from rocks by using their five-part jaw

____________________________________
o Use tube feet on flexible arms to capture plankton that float by on ocean
currents

____________________________________
o Move like a bulldozer across the ocean floor, taking in a mixture of sand
and detritus
Respiration

Echinoderms need to exchange carbon dioxide for oxygen

In most species the thin walled tissue of the tube feet forms the main respiratory
surface

In some species small outgrowths called ________________________ also
function in gas exchange
Internal Transport

The functions of transporting oxygen, food, and wastes are shared by different
systems in echinoderms

The distribution of nutrients is performed primarily by the digestive glands and
the fluid within the body cavity
Excretion

Solid wastes are released through the ___________ in the form of
________________

Excrete nitrogen-containing wastes primarily in the form of ammonia

Wastes seem to be excreted in many of the same places around the body in which
gas exchange takes place – ___________________________________________
Response

Have primitive nervous systems

Have a ______________________________ that surrounds the mouth and radial
nerves that connect the ring with the body sections

Also have _______________________________________________ to help
them tell whether it is night or day

Many echinoderms hide under rocks and in crevices by day, coming out to feed at
night, when most predators are asleep
Movement

Most echinoderms use tube feet and thin layers of muscle fibers attached to the
plates of the endoskeleton to move

Mobility is determined by the structure of the endoskeleton
o Some plates are ____________________
o Some have _____________________________________
Reproduction

Most are either _____________ or _________________

Some are ____________________________________

In starfish, the sperm and egg are produced in ______________________ or
________________________ which fill the arms during the reproductive season

Shed their sperm and eggs into the ____________________

___________________ swim around for some time

Eventually, they will swim to the __________________________________,
where they mature and metamorphose into adults that have
________________________________________
The Echinoderm Classes

Almost ________________________ of living echinoderms

Found in almost every ocean in the world

No echinoderms have ever entered ________________________________, and
they cannot survive for long on land

Echinoderms are remarkably _______________________ in appearance
Starfish

Contains the common starfish, which are also known as ____________________

Occur in many ______________________

Many species have more than _____________________

Starfish creep slowly along the ocean bottom

Most are carnivores, preying upon the bivalves they encounter as they move

Some species are important predators in rocky areas along the coast
Brittle Stars

Live in tropical seas, especially on _____________________________

Look much like a common starfish, but they have longer, more flexible arms and
are able to move much more rapidly

Brittle stars protect themselves by ______________________________________
______________________________ when attacked

The detached parts keep wriggling violently, distracting predators, while the rest
of the animal escapes

Are filter and detritus feeders that hide by day and wander around in search of
food at night
Sea Urchins and Sand Dollars

Includes disk-shaped _____________________________, oval heart urchins, and
round ___________________________

Most are _________________________ that eat large quantities of algae

Others are detritus feeders

Heart urchins and sand dollars live hidden in burrows

Most sea urchins wedge themselves in crevices in rock during the day and only
come out at night

Many sea urchins have __________________________________
Sea Cucumbers

Look like warty moving pickles with a mouth at one end and an anus at the other

Most are _______________________________

Not numerous in shallow water

Herds containing hundreds of thousands of them often cover areas of the sea floor
at great depths

A few species expel ______________________________________________
that attach to a predator

The predator is immobilized as it is glued into a helpless ball
Sea Lilies and Feather Stars

These filter feeders, which have ________________________ long, feathery
arms, comprise the most ancient class of echinoderms

Not common today

Sea lilies are sessile animals that are attached to the ocean bottom by a long, stem
like stalk

Many feather stars live on coral reefs, where they perch on top of rocks at night
and use their tube feet to catch floating plankton
How Echinoderms Fit into the World

Numerous in most _______________________________________

Control the populations of other animals

Control the distribution of _______________________

Considered ____________________________ by some people

Useful as research subjects and as possible sources of ______________________