Chapter 23.6+ Echinoderms & Invertebrate Chordates 1
Echinodermata Echino = spiny Derma = skin 2
Echinoderms - Examples Sea stars Sea urchins Sand dollars Sea cucumbers Brittle stars 3
Last Group of Invertebrates 4
Animal Development Embryonic development Zygote Blastula Gastrula Blastopore 5
Protostomes Mouth develops near or at the blastopore 6
Deuterostomes Anus develops near or at the blastopore 7
Protostomes Proto first Stome mouth Includes: Acoelomates Coelomates Mollusks Annelids Arthropods 8
Deuterostomes Deutero = second Stome= mouth Includes: Coelomates Echinoderms Chordates 9
Echinoderm Characteristics First deuterostomes Evolutionary milestone All marine Water vascular system Coelomic circulation Coelomic respiration 10
Echinoderm Endoskeleton inside skeleton Calcium rich Located: Young inside tissues Adults-covered by thin skin Appears to be external Ossicles Interlocking plates embedded in skin Protection Muscle attachment Bear spines Often posionous 11
Echinoderm Endoskeleton Catch connective tissue Holds ossicles together Unique Adjustable stiffness Changes within seconds 12
Animal Symmetry 13
Echinoderm Symmetry Larvae Bilateral Adults Radial 5 part body plan Arms radiate from center Number of arms varies 14
Echinoderm Nervous System Radial symmetry No anterior No cephalization No brain or head Central ring of nerves Branches into all arms Each arm more or less independent 15
Echinoderm Water Vascular System Unique trait used for: Movement Gas exchange Feeding Water filled Ring canal surrounds central disk Stone canal connects madreporite to the radial canals Radial canals extend into each arm Tube feet Tiny suckers Thousands Water pressure allows extension and contraction Grab objects, help move 16
Echinoderm Water Vascular System Overall design 17
Sea Star Page 674 18
Circulation and Respiration Fluid filled coelom Functions as simple circulatory and respiratory systems Fluid carries nutrients and oxygen starfish dissection 9:30 19
Echinoderm Respiration Use diffusion Respiratory gases exchanged Skin gills Small, finger-like projections Increase surface area for gas exchange 20
Skin Gills 21
Echinoderm Digestion Complete system Mouth Stomach Small intestine Anus Sea stars are able to push stomach out of mouth! Pushes between 2 clam shells Digests clam body 22
Regeneration Regrowth of parts Ex: Sea star limbs can regrow as long as part of central disk (nervous sys) remains Each limb contains digestive and reproductive glands Ex: Sea cucumbers can regrow digestive system parts 23
Echinoderm Reproduction Most sexual; separate sexes External Egg and sperm fuse to form zygote Becomes free-floating larva Goes thru series of complex changes Settles to ocean floor and becomes adult 24
Echinoderm Diversity One of most numerous marine phyla ~20 extinct classes 5-6 living classes 25
Phylum Echinodermata 6 classes: 1) Crinoidea Sea lilies Feather stars 2) Asteroidea Sea stars 3) Ophiuroidea Brittle stars Sea baskets Echinoderms part 1 8:30 4) Echinoidea Sea urchins Sand dollars Sea bisquits 5) Holothuroidea Sea cucumbers?6) Concentricycloidea Sea daisies 26
1) Class Crinoidea Sea lilies and feather stars Most ancient living Different from other echinoderms: Mouth on upper surface 27
Sea Lilies Sessile Attached by stalk to ocean floor Stalk 60 cm long 28
Feather Stars Mass of feather like arms Radiate from tiny body Tube feet on arms Great range of colors 29
Feather Stars Attach themselves Use hook-like projections to hang on Sometimes crawl or swim 30
2) Class Asteroidea Most familiar group Sea stars 31
Sea Stars Some filter-feed Some opportunistic Eat whatever is available! Most carnivorous Important predators Prey on shell fish and coral 32
Sea Stars Crown-of-thorns Eats coral polyps Coral reefs = rainforests of the ocean 33
Crown of Thorns Largest sea star 0.5 meters across 20 or more arms Consumes 6 square meters annually! Can destroy coral reef ecosystems 34
Sea Stars Pedicellaria On ossicles Defensive Pincer-like Snap when touched Prevents small organisms attachment 35
3) Class Ophiuroidea Ex: Brittle Stars and Sea Baskets Largest class Slender arms Break easily Used for movement Live on ocean bottom Most filter feed Tube feet lack suckers Echinoderms Part 2, 8:30 36
4) Class Echinoidea Sea urchins, sea biscuits, and sand dollars Found on ocean bottoms 37
Sea Urchins Spines Moveable Often blunt Some have long, sharp spines Often spines are attached to venom glands 38
Sea Urchins Live on rocky substrates Graze on algae and encrusting animals Special feeding apparatus Aristotle s lantern Contains five projecting teeth 39
Sea Urchins Many species Some eat kelp Sea otters eat urchins When sea otters have disappeared, kelp forests are gone too WHY? These desolate places = urchin barrens 40
Sand Dollars Lack distinct arms Have flattened bodies Have projections that help them burrow Filter feed 41
Sea Biscuits Usually found on sediments Burrow through sand Feed by filtering A Sea Biscuit's Life 3:36 42
5) Class Holothuroidea Sea Cucumbers The ONLY members of this class Soft bodied Slug-like No arms; thick tentacles instead Ossicles small and not fused Tough, leathery exterior 43
Sea Cucumbers Feeding Mouth on one end Modified tube feet form tentacles Tentacles covered in mucus Trap plankton Draw tentacles in and clean Defense Release sticky threads from anus Sea cucumber defending itself against fearful young lady 4:16 44
Sea Cucumbers Economically important Gourmet food in Orient Processes the body wall Multimillion dollar industry Some produce toxins of interest to medicine Antimicrobial activity Anti-inflammatory activity 45
Sea Cucumbers 46
6) Class Concentricycloidea? Sea Daisies New class Discovered in 1986 off New Zealand s coast Disk shaped Diameter < 1 cm Tube feet on edge of disk Only a few species known 47
Changing gears... Moving on to a new phylum.... Some are invertebrates... Some aren t 48
Phylum Chordata CrashCourse on Chordates 12:08 49
Phylum Chordata 2 groups 1) Invertebrate chordates Urochordata tunicates Chephalochordata - lancelets 2) Vertebrate chordates All are deuterostomes All have endoskeletons Completely internal 50
4 Chordate Characteristics 1) Notochord noton = back in Greek chorda = cord in Greek Stiff rod allowing support Develops along back of embryo Place for muscle attachment Allows lateral bending 51
4 Chordate Characteristics 2) Nerve cord Single Hollow Dorsal to notochord Develops into brain & spinal cord Nerves are attached Go to all parts of body 52
4 Chordate Characteristics 3) Pharyngeal slits Slits through body wall in pharynx Located at back of throat Connects mouth to digestive tract and windpipe Water can enter/leave mouth without going through entire digestive system Close up during embryonic stages Terrestrial animals don t need gill slits! 53
4) Chordate Characteristics 4) Tail (Postanal) Extends beyond anus Contains muscle used for movement All 4 traits exist at some point in development Most usually lost by adulthood 54
Phylum Chordata 3 subphyla 1) Urochordata No backbone 2) Cephalochordata No backbone 3) Vertebrata Backbone!!! Majority of species 55
1) Subphylum Urochordata Tunicates Tough outer coat = tunic Commonly called sea squirts Shoot out a stream of water when touched 56
1)Subphylum Urochordata Found on ocean bottom Most are: Barrel shaped Sessile Filter feeders Tunicate facts 4:41 57
1) Subphylum Urochordata Adults retain pharyngeal slits Adults do not have: Nerve cord Notocord Postanal tail 58
1) Subphylum Urochordata Tunicates: 59
1) Subphylum Urochordata Tunicates 60
1) Subphylum Urochordata All hermaphrodites Some reproduce asexually Budding Can result in colonies of clones 61
Tunicate Anatomy Cilia beat within tunic Water enters incurrent siphon Circulates through body Passes through pharyngeal slits Exits through excurrent siphon 62
Tunicate feeding Filter feeders Water passes over pharyngeal slits Food filtered Drawn into stomach Undigested food to anus and out excurrent siphon tunicate trap :22 63
Tunicate Anatomy Hearth Circulation can switch directions! 64
2) Subphylum Cephalochordata Lancelets Named for bladelike shape Resemble fish (ARE NOT FISH) Small (5cm) Marine 65
2) Subphylum Cephalochordata Scaleless World wide in shallow ocean water Often only mouth protrudes from sediment amphioxus 3:25 66
Lancelet Anatomy Filter feed Cilia draw water into mouth and pharynx Exit through pharyngeal slits Eat microscopic protists Separate sexes 67
Last Group of Invertebrates! 68
Big Ideas 69