Chapter Echinoderms & Invertebrate Chordates

Transcription

1 Chapter Echinoderms & Invertebrate Chordates 1

2 Echinodermata Echino = spiny Derma = skin 2

3 Echinoderms - Examples Sea stars Sea urchins Sand dollars Sea cucumbers Brittle stars 3

4 Last Group of Invertebrates 4

5 Animal Development Embryonic development Zygote Blastula Gastrula Blastopore 5

6 Protostomes Mouth develops near or at the blastopore 6

7 Deuterostomes Anus develops near or at the blastopore 7

8 Protostomes Proto first Stome mouth Includes: Acoelomates Coelomates Mollusks Annelids Arthropods 8

9 Deuterostomes Deutero = second Stome= mouth Includes: Coelomates Echinoderms Chordates 9

10 Echinoderm Characteristics First deuterostomes Evolutionary milestone All marine Water vascular system Coelomic circulation Coelomic respiration 10

11 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

12 Echinoderm Endoskeleton Catch connective tissue Holds ossicles together Unique Adjustable stiffness Changes within seconds 12

13 Animal Symmetry 13

14 Echinoderm Symmetry Larvae Bilateral Adults Radial 5 part body plan Arms radiate from center Number of arms varies 14

15 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

16 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

17 Echinoderm Water Vascular System Overall design 17

18 Sea Star Page

19 Circulation and Respiration Fluid filled coelom Functions as simple circulatory and respiratory systems Fluid carries nutrients and oxygen starfish dissection 9:30 19

20 Echinoderm Respiration Use diffusion Respiratory gases exchanged Skin gills Small, finger-like projections Increase surface area for gas exchange 20

21 Skin Gills 21

22 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

23 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

24 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

25 Echinoderm Diversity One of most numerous marine phyla ~20 extinct classes 5-6 living classes 25

26 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

27 1) Class Crinoidea Sea lilies and feather stars Most ancient living Different from other echinoderms: Mouth on upper surface 27

28 Sea Lilies Sessile Attached by stalk to ocean floor Stalk 60 cm long 28

29 Feather Stars Mass of feather like arms Radiate from tiny body Tube feet on arms Great range of colors 29

30 Feather Stars Attach themselves Use hook-like projections to hang on Sometimes crawl or swim 30

31 2) Class Asteroidea Most familiar group Sea stars 31

32 Sea Stars Some filter-feed Some opportunistic Eat whatever is available! Most carnivorous Important predators Prey on shell fish and coral 32

33 Sea Stars Crown-of-thorns Eats coral polyps Coral reefs = rainforests of the ocean 33

34 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

35 Sea Stars Pedicellaria On ossicles Defensive Pincer-like Snap when touched Prevents small organisms attachment 35

36 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

37 4) Class Echinoidea Sea urchins, sea biscuits, and sand dollars Found on ocean bottoms 37

38 Sea Urchins Spines Moveable Often blunt Some have long, sharp spines Often spines are attached to venom glands 38

39 Sea Urchins Live on rocky substrates Graze on algae and encrusting animals Special feeding apparatus Aristotle s lantern Contains five projecting teeth 39

40 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

41 Sand Dollars Lack distinct arms Have flattened bodies Have projections that help them burrow Filter feed 41

42 Sea Biscuits Usually found on sediments Burrow through sand Feed by filtering A Sea Biscuit's Life 3:36 42

43 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

44 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

45 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

46 Sea Cucumbers 46

47 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

48 Changing gears... Moving on to a new phylum.... Some are invertebrates... Some aren t 48

49 Phylum Chordata CrashCourse on Chordates 12:08 49

50 Phylum Chordata 2 groups 1) Invertebrate chordates Urochordata tunicates Chephalochordata - lancelets 2) Vertebrate chordates All are deuterostomes All have endoskeletons Completely internal 50

51 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

52 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

53 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

54 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

55 Phylum Chordata 3 subphyla 1) Urochordata No backbone 2) Cephalochordata No backbone 3) Vertebrata Backbone!!! Majority of species 55

56 1) Subphylum Urochordata Tunicates Tough outer coat = tunic Commonly called sea squirts Shoot out a stream of water when touched 56

57 1)Subphylum Urochordata Found on ocean bottom Most are: Barrel shaped Sessile Filter feeders Tunicate facts 4:41 57

58 1) Subphylum Urochordata Adults retain pharyngeal slits Adults do not have: Nerve cord Notocord Postanal tail 58

59 1) Subphylum Urochordata Tunicates: 59

60 1) Subphylum Urochordata Tunicates 60

61 1) Subphylum Urochordata All hermaphrodites Some reproduce asexually Budding Can result in colonies of clones 61

62 Tunicate Anatomy Cilia beat within tunic Water enters incurrent siphon Circulates through body Passes through pharyngeal slits Exits through excurrent siphon 62

63 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

64 Tunicate Anatomy Hearth Circulation can switch directions! 64

65 2) Subphylum Cephalochordata Lancelets Named for bladelike shape Resemble fish (ARE NOT FISH) Small (5cm) Marine 65

66 2) Subphylum Cephalochordata Scaleless World wide in shallow ocean water Often only mouth protrudes from sediment amphioxus 3:25 66

67 Lancelet Anatomy Filter feed Cilia draw water into mouth and pharynx Exit through pharyngeal slits Eat microscopic protists Separate sexes 67

68 Last Group of Invertebrates! 68

69 Big Ideas 69