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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.