1. Echinodermata and Invertebrate Chordates
Chapter 40

2. Phylum Echinodermata Characteristics
Age of echinoderms is estimated as more than 500 mil years
All marine
Known as spiny-skinned animals
Endoskeleton known as the test is made of calcium plates or ossicles with protruding spines
Includes sea stars, brittle stars, sand dollars, sea urchins, & sea cucumbers
Undergo metamorphosis from bilateral, free-swimming larva to sessile or sedentary adult
Larval stage known as dipleurula or bipinnaria
Adults have pentaradial ( 5 part) symmetry
Lack segmentation or metamerism
Coelomate
Breathe through skin gills as adults
Capable of extensive regeneration

3. Characteristics cont…
Ventral (lower) surface called the oral surface & where mouth is located
Dorsal (upper) surface known as aboral surface & where anus is located
Have a nervous system but no head or brain in adults
No circulatory, respiratory, or excretory systems
Have a network of water-filled canals called the water vascular system to help move & feed
Tube feet on the underside of arms help in moving & feeding
One-way digestive system consists of mouth with oral spines, gut, & anus
Deuterostomes (blastopore becomes the anus)
Separate sexes
Reproduce sexually & asexually

4. Phylum Echinodermata
Includes 5 classes:           * Crinoidea - sea lilies & feather stars           * Asteriodea - starfish           * Ophiuroidea - basket stars & brittle stars           * Echinoidea - sea urchins & sand dollars           * Holothuroidea - sea cucumbers

5. Class Crinoidea Characteristics
Sessile
Sea lilies & feather stars
Have a long stalk with branching arms that attach them to rocks & the ocean bottom
Can detach & move around
Mouth & anus on upper surface
May have 5 to 200 arms with sticky tube feet to help capture food (filter feeders) & take in oxygen
Common in areas with strong currents & usually nocturnal feeders

6. Class Crinoidea
                                                              SEA LILY
                                                              FEATHER STAR

7. Class Asteroidea Characteristics
Usually sedentary along shorelines
Starfish or sea stars
Come in a variety of colors
Prey on bivalve mollusks such as clams & oysters
Have 5 arms that can be regenerated
Arms project from the central disk
Mouth on oral surface (underside)

8. Class Asteroidea
                                      Starfish Feeding on Clam

9. Class Ophiuroidea Characteristics
Largest class of echinoderms
Includes basket stars & brittle stars
Live on the ocean bottom beneath stones, in crevices, or in holes
Have long, narrow arms resembling a tangle of snakes
Arms readily break off & regenerate
Move quicker than starfish
Feed by raking in food with arms or trapping it with its tube feet

10. Class Ophiuroidea
                                                                         BASKET STAR
                                                                         BRITTLE STAR

11. Class Echinoidea Characteristics
Includes sea urchins & sand dollars
Internal organs enclosed by endoskeleton or test made of fused skeletal plates
Body shaped like a sphere (sea urchin) or a flattened disk (sand dollar)
Lack arms
Bodies covered with movable spines
Have a jawlike, crushing structure called Aristotle's lantern to grind food
Use tube feet to move

12. Class Echinoidea Characteristics cont…
Sea Urchins:         * Spherical shape         * Live on ocean bottom         * Scrape algae to feed         * Long, barbed spines make venom for protection
Sand Dollars:         * Flattened body         * Live in sand along coastlines         * Shallow burrowers         * Have short spines

13. Class Echinoidea
                                                                    SEA URCHIN
                                                               SAND DOLLAR

14. Class Holothuroidea Characteristics
Includes sea cucumber
Lack arms
Shaped like a pickle or cucumber
Live on ocean bottoms hiding in caves during the day 
Have a soft body with a tough, leathery outer skin
Five rows of tube feet run lengthwise on the aboral (top) surface of the body
Have a fringe of tentacles (modified tube feet) surrounding the mouth to sweep in food & water
Tentacles have sticky ends to collect plankton
Show bilateral symmetry
Can eject parts of their internal organs (evisceration) to scare predators; regenerate these structures in days

15. Class Holothuroidea
                                                                    SEA CUCUMBER

16. Structure & Function of Starfish Body Plan
Range in size from 1 centimeter to 1 meter
Mouth located on oral surface (underside)
Have an endoskeleton made of calcium plates
Sharp, protective spines made of calcium plates called ossicles found under the skin on the aboral (top) surface
Have pedicellariae or tiny, forcep-like structures surrounding their spines to help clean the body surface

17. Structure & Function of Starfish Body Plan
                                       ABORAL SURFACE

18. Structure & Function of Starfish Water Vascular System
Network of canals creating hydrostatic pressure to help the starfish move
Water enters through sieve plate or madreporite on aboral surface into a short, straight stone canal
Stone canal connects to a circular canal around the mouth called the ring canal
Five radial canals extend down each arm & are connected to the ring canal
Radial canals carry water to hundreds of paired tube feet

19.                                                   WATER VASCULAR SYSTEM

20. Structure & Function of Starfish Water Vascular System
Bulb-like sacs or ampulla on the upper end of each tube foot contract & create suction to help move, attach, or open bivalves
Rows of tube feet on oral surface (underside) are found in ambulcaral grooves under each arm

21. Structure & Function of Starfish Water Vascular System
                                                                           TUBE FEET
                                    Tube Feet in Ambulcaral Grooves

22. Feeding & Digestion
Tube feet attach to bivalve mollusk shells & create suction to pull valves apart slightly
Starfish everts (turns inside out) its stomach through its mouth & inserts it into prey
Stomach secretes enzymes to partially digest bivalve then stomach withdrawn & digestion completed inside starfish

23. Other Body Systems No circulatory, excretory, or respiratory systems
Coelomic fluid bathes organs & distributes food & oxygen
Gas exchange occurs through skin gills & diffusion into the tube feet
No head or brain
Have a nerve ring surrounding the mouth that branch into nerve cords down each arm
Eyespots on the tips of each arm detect light
Tube feet respond to touch

24. Reproduction Separate sexes
Two gonads (ovaries or testes) in each arm produce eggs or sperm
Have external fertilization
Females produce up to 200,000,000 eggs per season
Fertilized eggs hatch into bipinnaria larva which settles to the bottom after 2 years & changes into adult
Asexually reproduce by regenerating arms

25. Characteristics of Chordates
All chordates have a notochord, dorsal nerve cord, pharyngeal pouches, & postanal tail at some time in their life
Notochord is a firm, flexible rod of tissue located on the dorsal side of the body that becomes part of the endoskeleton in vertebrates
Dorsal nerve cord is a hollow tube lying dorsal to the notochord that becomes the brain & spinal cord in vertebrates
Pharyngeal pouches are small outpockets of the anterior part of the digestive tract that become gills in aquatic chordates & jaws, inner ear, & tonsils in terrestrial chordates
Postanal tail consists of muscle tissue & lies behind the posterior opening of the digestive tract

26. Characteristics of Chordates

27. Subphyla of Chordates
The Phylum Chordata  includes all of the vertebrates, as well as two groups of marine animals that lack backbones and are called invertebrate chordates
The phylum is divided into three subphyla, determined by the development of the notochord
Subphylum Cephalochordata contains about 24 species of blade-shaped animals known as lancelates that retain the notochord, dorsal nerve chord, pharyngeal pouches, and postanal tail throughout their life

29. Subphyla of Chordates cont…
Subphylum Urochordata  contains 2,000 species commonly called tunicates because their bodies are covered by a tough covering, or tunic      * Called sea squirts because they shoot out a stream of water when touched      *Sessile, barrel-shaped, filter feeding animals that live on the sea bottom      *Adults have a pouch-like pharynx with slits      *Adults do not have a notochord, dorsal nerve cord, or postanal tail

31. Subphyla of Chordates cont…
Subphylum Vertebrata is the largest subphylum in which the notochord is replaced with vertebrae *  Skeletons consist of bone &/or cartilage * Brain is protected by a cranium * Well developed 4 chambered heart with a closed circulatory system * Includes fish, amphibians, reptiles, birds, & mammals

32. Chordate Characteristics
Feature
Vertebrata
Cephalo-chordata
Uro-chordata
Notochord
Dorsal Nerve cord
Pharyngeal pouch
Postanal tail