Echinoderms &
Chordates
Phylum Echinodermata
(echinoderms)
• About 6,000 species
• All _______________
Phylum Echinodermata
(echinoderms)
• Eucoelomates, triploblastic
Phylum Echinodermata
(echinoderms)
• Eucoelomates, triploblastic
• Pentamerous (5-part) radial symmetry as
adults
• Parts arranged around oral/aboral axis
Phylum Echinodermata
(echinoderms)
• Why not in ___________? Larva bilaterally
symmetrical!
Phylum Echinodermata
(echinoderms)
• Calcareous endoskeleton. Plates form
surrounded by tissues.
• Arises from mesoderm. “echino-” means
spiny, “-derm” means skin.
Phylum Echinodermata
• Water vascular system in _____________
• Connect to tube feet
• Note madreporite on aboral surface of starfish
(takes water into system)
Phylum Echinodermata
• Tube feet in action
Phylum Echinodermata
(echinoderms)
• Complete digestive system
• Reproduction: have good regeneration
abilities, some can break into parts and
reproduce asexually.
Phylum Echinodermata
(echinoderms)
• Most reproduce sexually
• Dioecious, fertilization external
Phylum Echinodermata
• No head or well developed brain (nerve ring)
• No excretory organs (no flame cells, nephridia,
etc.)
• No respiratory system (tube feet and papulae
help exchange gases)
Phylum Echinodermata
(echinoderms)
• Deuterostomes
Phylum Echinodermata
(echinoderms)
•
•
•
•
•
Class Crinoidea (sea lilies/feather stars)
Class Asteroidea (sea stars)
Class Ophiuroidea (brittle stars)
Class Echinoidea (sand dollars and sea urchins)
Class Holothuroidea (sea cucumbers)
Phylum Echinodermata
(echinoderms)
• Class Crinoidea (sea lilies/feather stars)
– Sessile for some or all of life. Add new __________ as
they grow.
– Have mouth and anus on upper surface.
Phylum Echinodermata
• Class Crinoidea (sea lilies/feather stars)
– Glorious fossil past (6000 fossil species, 600
living ones).
Wisconsin
Phylum Echinodermata
(echinoderms)
•
•
•
•
•
Class Crinoidea (sea lilies/feather stars)
Class Asteroidea (sea stars)
Class Ophiuroidea (brittle stars)
Class Echinoidea (sand dollars and sea urchins)
Class Holothuroidea (sea cucumbers)
Phylum Echinodermata
(echinoderms)
• Class Asteroidea (sea stars)
– 1500 species. Active and important marine predators
– Move about on tube feet
Phylum Echinodermata
(echinoderms)
• Class Asteroidea (sea stars)
– Predation may cause problems
– Ex, crown of thorns starfish (coral predator)
Phylum Echinodermata
(echinoderms)
• Class Asteroidea (sea stars)
– The rest of the story: part of
problem may be
overcollecting of tritons, a
gastropod that preys on these
starfish
Phylum Echinodermata
(echinoderms)
•
•
•
•
•
Class Crinoidea (sea lilies/feather stars)
Class Asteroidea (sea stars)
Class Ophiuroidea (brittle stars)
Class Echinoidea (sand dollars and sea urchins)
Class Holothuroidea (sea cucumbers)
Phylum Echinodermata
(echinoderms)
• Class Ophiuroidea (brittle stars)
– 2000 species. Abundant, nocturnal. Move using
two arms at a time
– Feed on plankton and organic debris with tube
feet.
Phylum Echinodermata
(echinoderms)
•
•
•
•
•
Class Crinoidea (sea lilies/feather stars)
Class Asteroidea (sea stars)
Class Ophiuroidea (brittle stars)
Class Echinoidea (sand dollars and sea urchins)
Class Holothuroidea (sea cucumbers)
Phylum Echinodermata
• Class Echinoidea (sea urchins/sand dollars)
– Lack arms. 1000 species. Endoskeleton of
fused calcareous plates
– No arms or rays. Have rows of spines and tube
feet. Spines and feet moveable.
Phylum Echinodermata
(echinoderms)
• Class Echinoidea (sea urchins/sand dollars)
– Sea urchins: long spines
– Sand dollars: short spines
Phylum Echinodermata
(echinoderms)
• Class Echinoidea (sea urchins/sand dollars)
– Pedicillariae. Discourage small invertebrates
from settling on surface.
Phylum Echinodermata
(echinoderms)
• Class Echinoidea (sea urchins/sand dollars)
– Aristotle’s lantern: complex chewing apparatus.
Phylum Echinodermata
• Can be important members of marine
ecosystems
• Ex, sea urchins as herbivores
Urchins, sea otters, and kelps
• Sea otters hunted
almost to extinction on
West Coast
• Now expanding back
• Top carnivores
(almost): eat mussels,
abalone, sea urchins.
Purple sea urchin
Urchins, sea otters, and kelps
• Urchins eat __________
of kelp
• Fewer urchins now that
otters are back.
Urchins, sea otters, and kelps
• Giant kelp forests
recovering as otters return.
• Fish and other associates
rebounding.
Sea urchins
• Eggs (roe) edible, delicacy (known as uni in sushi bars)
Phylum Echinodermata
(echinoderms)
•
•
•
•
•
Class Crinoidea (sea lilies/feather stars)
Class Asteroidea (sea stars)
Class Ophiuroidea (brittle stars)
Class Echinoidea (sand dollars and sea urchins)
Class Holothuroidea (sea cucumbers)
Phylum Echinodermata
• Class Holothuroidea (sea cucumbers)
– Elongate
– Soft bodied (endoskeleton plates reduced or
absent)
– Often with feeding tentacles around mouth
•
Phylum
Echinodermata
Class Holothuroidea (sea
cucumbers)
– Have respiratory organ (respiratory
tree) (11, F), arising from cloaca (12,
G: near anus, 13)
– Gonads (8, H)
– Intestine (10, I)
Phylum Echinodermata
• Class Holothuroidea (sea cucumbers)
– Symbiosis story: black pearlfish can be found
living in _________ of sea cucumbers
Phylum Echinodermata
• Class Holothuroidea (sea cucumbers)
– Sea cucumber defense tactic: regurgitate
internal organs and _____________ them later
Phylum Echinodermata
(echinoderms)
• Class Holothuroidea (sea cucumbers)
– Edible: braised sea cucumber with tea leaves
Phylum Chordata (chordates)
• About 43,000 species
• Triploblastic, eucoelomates
Phylum Chordata (chordates)
• Bilateral symmetry
• Deuterostomes
Segmentation
• Present in chordates
• Often visible in embryo
Internal skeleton
• Differs from echinoderms. Rodlike, deeper
in body. Gives attachment points for
muscles.
Human skeleton
4 Key Features
• 1) Hollow (tubular!) nerve cord
under *dorsal* surface
4 Key Features
• 1) Hollow (tubular!) nerve
cord under *dorsal* surface
• Becomes brain and spinal cord
• *Invertebrates usually have
ventral nerve cords.
4 Key Features
• 2) Notochord: flexible rod just under nerve
cord. Originally served as muscle
attachment point
4 Key Features
• 3) Pharyngeal pouches in embryo
• In humans, only one remains to form
Eustachian tubes connecting inner ear to
__________.
4 Key Features
• 4) Postanal tail (at least during embryonic
stages). Nearly all other animals with
terminal anus
Chordate survey
• Subphylum Urochordata (tunicates)
• Subphylum Cephalochordata (lancelets)
• Subphylum Vertebrata (vertebrates)
Chordate survey
• Subphylum Urochordata (tunicates)
– Marine. 1300 species.
Chordate survey
• Subphylum Urochordata (tunicates)
– Adult sessile, filter feeder.
– Has holdfast, siphons (incurrent & excurrent,
pharynx). Cilia in pharynx create water
current.
Chordate survey
• Subphylum Urochordata
(tunicates)
– Pharynx used to feed,
traps food in mucus on
endostyle
– Pharynx has gill slits for
breathing
– Many adults secrete
tunic: tough sac of
______________ around
body.
Chordate survey
• Subphylum Urochordata (tunicates)
• Subphylum Cephalochordata (lancelets)
• Subphylum Vertebrata (vertebrates)
Chordate survey
• Subphylum Cephalochordata (lancelets)
– Marine. 20 species.
– Ex, Amphioxus or Branchiostoma
Chordate survey
• Subphylum Cephalochordata (lancelets)
– Filter feeder, can swim
– Oral hood has tentacles (sensory)
– Cilia create water current, used for breathing and filter
feeding. Water exits via _________________.
Chordate survey
• Subphylum Cephalochordata (lancelets)
– No head, brain, eyes, etc.
– Skin only 1 cell layer thick (vertebrates with multilayered skin)
– ________________: segmented muscles.
Chordate survey
• Subphylum Cephalochordata (lancelets)
– Model version (as seen in lab)
Chordate survey
• Subphylum Urochordata (tunicates)
• Subphylum Cephalochordata (lancelets)
• Subphylum Vertebrata (vertebrates)
Subphylum Vertebrata
(vertebrates)
• Distinctive
features
– 1) Have vertebral
column. Bony
segments replace
__________,
enclose spinal
cord
Subphylum Vertebrata
(vertebrates)
• Distinctive features
– 2) Have well-developed head (with skull and
brain)
Subphylum Vertebrata
(vertebrates)
• Other features
– 3) Neural crest in embryo. Cells migrate to
form many tissues (parts of muscle, nerve, skin,
systems, etc.) in various places in body.
Subphylum Vertebrata
(vertebrates)
• Other features
– 4) Internal organs: liver, kidneys, endocrine
glands, heart and closed circulatory system
– 5) Endoskeleton of _________ (protein) or bone
(protein and calcium crystals). Bone strong but
not brittle. Can make big bodies this way.
Chordate survey
• Subphylum Vertebrata (vertebrates)
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Class Agnatha
Class Chondrichthyes
Class Osteichthyes
Class Amphibia
Class Reptilia
Class Aves
Class Mammalia