Echinoderms

Echinoderms

Echinoderms

• The name Echinoderm comes from the Greek echinos meaning “spiny”and derma meaning “skin”

Classes• Asteroidea (Sea Star)

• Crinoidea (Sea Lillies)

• Ophiuroidea (Brittle Stars)

• Echinoidea (Sea Urchins)

• Holothuroidea (Sea Cucumbers)

• There are 20 extinct classes

Objectives • Describe the major characteristics

of echinoderms

• Compare and contrast the lifestyles of the organisms each of the five echinoderm classes

• Describe how sea stars feed

Describe the major characteristics of echinoderms

• Endoskeleton – Living tissue with endoskeleton underneath – Composed Of Ossicles – Functions like Arthropod’s Exoskeleton,

providing muscle attachment sites – shell like protection

Objective Continued

• Five Part Radial Symmetry – arms extending radially from a central

point

• Water Vascular System– water filled system of interconnected

canals and tube feet

How They MoveEchinoderms

move by using their tube feet

They have several thousand on their arms or undersides

Tube feet

Tube feet may:have good suctiontaper to a pointor be adapted to a certain function.

Mucus contains adhesive and de- adhesive.

Objective Continued

• Coelomic circulation and respiration– particles move easily through large

fluid filled coelom

Compare Contrast Lifestyles of Five Classes

• Sea Stars– 1,500 species – Most important predator– five part body plan– carnivore

Crown-Of-Thorns

•Crown-of-thorns consumes cnidarians.

Sea Star Larva

• Larva and adults have different body plans. The adult is radially symmetric and the larva is bilaterally symmetric

Objective Two Continued

• Sea Lilies– most primitive

– sessile

– five part body plan

– mouth located on upper surface

Objective Two Continued

• Brittle Stars– 2,000 species

– slender arms that move in pairs

– sometimes grouped with sea stars

– five part body plan

Objective Two Continued

• Sea Urchins and Sand Dollars– lack arms

– five part body plan

– hard endoskeleton

– 900 species

Heart and Fire Urchins

Objective Two Continued

• Sea Cucumbers– 1,500 species

– Ossicles are small and not connected (soft-bodied)

– tube feet modified into tentacles for eating

Sea Cucumbers

• Mouth surrounded by dozens of tube feet; modified into tentacles.

Sea Cucumber

Describe How Sea Stars Feed• Active Predator and Carnivore

– eat shell fish and other star fishes

– mud swallowers

– some extrude their mouth to digest externally and internally

All Echinoderms Share Four Major Characteristics

• Objective : Describe the major characteristics of echinoderms.

• Echinoderms have an endoskeleton - Composed of individual plates called ossicles.

Echinoderm characteristics

• Coelomic circulation and respiration : Body cavity is a simple circulatory system. Respiration performed by skin gills.

Characteristics of Echinoderms

• Five-Part radial symmetry : Five arms extending radially from a central point.

• Water-Vascular system : Water filled system of canals and tube feet.

Sexual ReproductionMost

echinoderms get together before spawning to increase chances of fertilization

Asexual ReproductionSuccessful

regeneration, or regrowth, requires a body wall that can be torn easily and reseal wounds easily.

Indirect Development

Fertilized egg divides many times to produce a hollow ball of cells known as the Blastula

Indirect Development

The ball of cells grows inward to form a cavity which will become a simple, primitive gut

.

Pro-Mouth

Deudi-PoopAnus

Blastopore

Athletes

Phylogenetic Tree

Blankenship

Question #1

• List the four major echinoderm characteristics.

• Endoskeleton (Exoskeleton Like)

• Five Part Radial Symmetry

• Water Vascular System

• Coelomic Circulation and Respiration

Question #2

• Explain why some echinoderms have

bodies that are softer than others.

• Some do not have a fused skeleton, therefore are soft-bodied.

Question #3

• Compare and contrast the feeding habits of

a sea star and a sea cucumber

• Both sea stars and cucumbers have tube feet, but the cucumbers’ have developed into feeding tentacles.

Question #4• Name the echinoderms that are completely

sessile, and describe their basic structure.

• Sea lilies are sessile. Sea lilies are attached to the ocean floor by a stalk. Feather stars have a stalk in early development, but do not remain sessile.

Chordates

96% are Vertebrates.

What is a chordate?

• A chordate is an animal that has, for at least some stage of its life, a dorsal, hollow nerve cord; a notochord; pharyngeal pouches; and a tail that extends beyond the anus.

Characteristics of Chordates

• All chordates share four characteristics:• 1) dorsal, hollow nerve cord• 2) notochord• 3) pharyngeal pouches• 4) a tail that extends beyond the anus• Some chordates have these characteristics

as adults. Others have them only as embryos.

Chordate Structure

Notochord

• A notochord is a long supporting rod that runs through the body just below the nerve cord.

• Most chordates only have a notochord only when they’re embryos.

Pharyngeal pouches

• Are paired structures in the throat

• In some amphibians they are slits that connect the pouches to the outside of the body.

Pharyngeal Pouches• Pharyngeal pouches are paired structures in the

throat (pharynx) region.

• In fishes and amphibians, slits develop that connect the pharyngeal pouches to the outside of the body.

• The slits may then develop gills that are used for gas exchange.

Vertebrae

• Individual segments that make up the backbone. • It encloses and protects the spinal cord. It also

provides support. • Provides muscles a place to attach and is part of the

endoskeleton. • Grows when the animal grows and does not need to

be shed.• Contains living cells and non-living material and

the living cells make the non-living materials.

Although nonvertebrates chordates lack a vertebral column, they share a common ancestor with vertebrates.

Nonvertebrate Chordates

Nonvertebrate Chordates

• The two groups of Nonvertebrate chordates are tunicates and lancelets.

• Both are soft bodied organisms.

• They contain hollow nerve cords, notochord, pharyngeal pouches, and a tail (at some time of their life).

Tunicates

• They are filter feeders.

• They are in the subphylum urochordata.

• When they are adults they do not have a notochord or a tail.

• Blue lollypop tunicate

blue palm coral.

Non Vertebrate Chordates

Sea squirt

• Sea squirt colonies

Lancelets

Subphylum : Cephalochordata

They are usually found buried in sand in shallow parts of temperate or tropical seas.

Lancelets have a closed circulatory system, rather than an open circulatory system

They have a definite head region where it’s mouth is located. -The mouth opens up to the pharynx lined with gill slits.

Questions and Answers!

What is a Chordate?

Answer!

• Animal that has:

• A dorsal, ventral hollow nerve cord

• Notochord

• Pharynegeal pouches

• Tail extending beyond the anus

What are notochords and pharyngeal pouches?

Answer!

• A notochord is a long, supporting rod that runs through the body just below the nerve cord. Usually, chordates only have them when they are embryos.

• Pharyngeal pouches are paired structures in the throat region. In some chordates, they may develop into gills.

What is a vertebrae?

Answer!

• Vertebrae are individual segments of the backbone.

What are tunicates and lancelets?

Answer!

• Tunicates are filter-feeders. They don’t have tails or notochords in the adult stage.

• Lancelets are small fish-like creatures who live in sandy ocean bottoms, with a definite head region containing a mouth. They have a closed circulatory system.