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•  Levels of
complexity change
(become more
complex) as we
move up the
evolutionary tree
•
Ancient animals
are no better or
worse adapted than
more complex
animals. Its all
about survival.
Sponges: Porifera pore bearer •  No real symmetry, associations of loosely
aggregated cells - very simple!
•  Coanocytes (flagellated), collar cells, allow for
food intake and O2. Osculum is excurrent pore
(can have several), pore cells intake water
•  Skeleton Spicules (CaCO3, or SiO2), or spongin
(household sponges)
•  Ecology: sessile, benthic, filter feeder. Encrusting
and upright, and boring
•  Most are hermaphrodites: eggs and sperm
(broadcast). Fertilization is internal. Also have
asexual reproduction: budding, re-aggregation
Lophophorates
Ctenophores here too
Sponges are Suspension Feeders
Choanocytes or Collar cells - flagellated
food-trapping cells of a sponge that
generate a current through the pores
Water out
through
Osculum
Water
in through Pore Cells
Water
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Cnidaria
Phylum Cnidaria
•  Radial symmetry
–  similar parts of the body are repeated around the
center. No front or back, No head
•  Oral surface (mouth side)
•  aboral surface (opposite of mouth side)
•  Two Body Forms
–  Polyp -cylindrical and usually attached
•  Corals,
•  Anemones
•  many colonial hydroids
–  Medusa - umbrella-like swimming form
•  upside-down polyp adapted for swimming
Polyp
Medusa
•  Diverse forms: jellyfish, corals, anemones, sea fans etc.
Stinging cells = nematocysts
•  Gastrovascular cavity digestion and absorbtion of
nutrients. Waste through mouth! Respiration occurs
through diffusion. •  Hydrostatic (water) skeleton
•  Ecology: sessile and benthic, as well as free swimming
(planktonic). Filter feeders and predators. Some are
colonial animals. (corals, sea fans, gorgonians, man-owar). Some like man-o-war and by the wind sailors
have sails to aid in movement!
Feeding Polyps
on colonial hydroid
Phylum Cnidaria
Phylum Cnidaria
•  Some have a two phase life cycle! Polyp and medusa
•  Symbiosis is common with zooxanthellae: 95% of food
and formation of calcareous skeleton.
•  Sex: Two phase life cycle (polymorphism)=sessile
polyp phase and mobile medusa phase. Sexual rep is
usually by medusa (eggs and sperm by broadcast
spawning, or internal fertilization). Polyp also
undergoes asexual budding
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Phylum Cnidaria
•  Some have a two phase life cycle! Polyp and medusa
Phylum Cnidaria Class Hydrozoa:
siphonophores
Aurelia: one of our Jellyfish (scyphozoan)
Phylum Cnidaria, class scyphozoa
Jellyfish and friends
Stinging cells
- unique to Cnidaria
Fluid filled capsule
Nematocysts
•  Nematocysts discharge on contact and with other stimuli (e.g. fresh
water!)
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Anthozoa - corals and anemones
Coral Polyp
•  Zooxanthellae
–  photosynthetic dinoflagellates (Kingdom: Protista) that
are adapted to live within corals.
Tentacles Zooxanthellae
Mouth
Phylum Ctenophora
Gut
Phylum: Ctenophora
•  Characteristics of Comb Jellies
 About 100 species - more????
 8 rows of ciliary combs (ctenes)
 Bi-radial symmetry
 Cilia beat continuously
•  Light is refracted off the cilia giving a prism-like
color effect
 Respiration occurs at body surface
 some have tentacles with sticky cells called
colloblasts used to capture prey
 cells and tissues are organized into organs
(rudimentary)
 simple Gut (single opening)
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Phylum: Ctenophora
•  Natural history of Comb Jellies
–  No segmentation; No circulatory
system
–  length from a few mm (sea
gooseberry) to 2 meters long
(venus s girdle)
–  Most are pelagic, Found in warm
and cold oceans - many are deep
sea and bioluminescent
–  Carnivores (e.g. eat fish larvae)
–  Hermaphrodites – broadcast
–  Lots we don t know!
Phylum Platyhelminthes:
flatworms
•  As many as 20,000 species!
•  CNS, Brain (agg. Of nerve cells in head region).
Nerve cords and muscular system. •  Many (such as flukes) are parasites (eg.
tapeworms – one is 40 feet long – in sperm
whales)
•  Bilateral
•  Organs and organ systems, nerves, brain, CNS,
muscles
•  No skeleton
•  Variety of functions (parasites, free living etc.)
•  Sexual, most have larval stage
Flatworms:
Phylum: Platyhelmenthes
Class Turbellaria
Ph Nemertea (ribbon worms),
Ph Nematoda (roundworms)
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Phylum Nematoda (roundworms)
Lophophorates: bilateral
symmetry
•  Bilateral symmetry
•  dig tract, and true
organs.
•  Hydrostatic skeleton
Plumatella fungosa
•  Huge #s in sediments,
decomposers, parasites, •  Sexual reproduction
with larvae. •  Can be seen in fish
flesh!
Bugula turbinata
Lichenopora hispida
Lophophorates: Lophophore=set of ciliated
tentacles arranged in a horseshoe).
•  Suspension feeders, mostly colonial (individual zooids), live in area of
low sedimentation
•  Bilateral
•  Unsegmented, colonial. U shaped gut
•  Exoskeleton of a variety of shapes
•  Benthic filterfeeders
•  Sexual and asexual.
•  Phylum Bryozoa: look like colonial hydrozoans. 4000 species,
delicate colonies. Retractable lophophore. Zooids show task
specialization.
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Polychaete worms (Phylum Annelida)
Phylum Annelida - Class Polychaeta
Class Polychaeta: most annelid species are here. 6,000 sp.
Mostly marine. 5-10 cm long. Live singly or in aggregations.
Build tubes made with lots of different things. Cilia and mucus
aid in feeding.
Phylum Annelida: segmented
worms
•  bilateral
•  Segmentation •  Gut cavity, complex movement and systems. Makes them
good crawlers and burrowers. •  2 Ventral nerve cords : peristaltic movement. Each
segment has kidneys for nitrogenous waste, and
parapodia with setae for movement. •  Closed circulatory system. •  Have gills
•  Hydrostatic skeleton - many have tubes etc!
•  See ploychaeta: deposit feeders and suspension feeders:
active and passive, and carnivorous. Some crawl.
•  Sexual. Trochophore larvae. often timed with phases of
moon.
Phylum sipuncula: peanut worms
Diopatra ornata
Ornate Tube Worm
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Phylum Sipuncula (peanut worms). •  All marine. 350 sp, benthic. Most intertidal, few
deep sea.
•  Bilateral
•  Unsegmented. Can curl in to look like peanut.
Mouth and anus at same end
•  Hydrostatic
•  Burrows (open at one end). Calcarous tubes or
burrows.
•  Sexual: gametes released through temporary
gonads. External fertilization
Phylum Echiura: spoon worms. About 100 sp. Fat innkeeper (Urechis Caupo). Burrow with
commenal creatures in mud. Sweep detritus with
proboscis and urechis uses a mucus net. Pumps
water through burrow and through net. Close
relatives of annelids.
Ph. Echiura: fat innkeeper worm
Phylum Cheatognatha: arrow worms. Only about
100 sp. •  Bilateral
•  Unsegmented, flattened, quick movements, small
body (high SA/V ratio means they don t have
resp. circ or excret. Systems.). Cilia serve to
notify them of movements in the water (like shark
lateral line system)
•  Hydrostatic
•  Predators, planktonic
•  Hermaphrodites
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Arrow worms: cheatognaths
Phylum Mollusca
•  Successful, more species of this phylum than any other in the
oceans. Diversity of shape and diversity of habitats that they
inhabit is high.
•  110,000 species: second only to arthropods
•
Soft bodied with a mantle that produces a shell (CaCo3)
•
Unsegmented and bilateral symmetry
•
Foot – ventral and muscular for locomotion
•
Radula – ribbon of teeth for rasping, made of
•
chitin.
•  Separate mouth and anus
•
Circulatory system – most open, cephalpods
•
closed (Blood remains in vessels)
•
Reproduction – dioecious and hermaphroditic, –  most have trochophore larvae to veliger
Some are benthic, some are pelagic, and they live from the
intertidal to the deep sea. Some are predators, some are
herbivores (grazers), while still others are filter feeders.
•
•
Class Gastropoda – "stomach footed"– snails, ~ 90,000 species! Nudibranchs, limpets Feed with radula –rasping tongue, coiled
shell (most),
Graze, some are sessile, most are motile
Class Bivalvia – clams, mussels,oysters
~3000 species
2 shells, crystalline style (enzyme
secretion), siphon, foot, gills, pearls
laterally compressed, some burrow, bore, or
attach to hard substrate.
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•
Class Cephalopoda – "head foot" ~600 species
Siphon for jet propulsion, funnel, ink, pen, beak
Active body plan of molluscs
– octopuses – 8 arms, no shell, bottom and crevice dwellers, hunters
– squid – 10 arms, 2 tentalcles, "pen", largest
invertebrate...
– cuttlefish – 8 arms, 2 tentacles, cuttle bone
•  Class Polylacophora ~
– Chitons, 8 plate like shells, radula, foot ~600 sp
Bivalvia
Cephalopoda
Phylum Mollusca - Class Polyplacophora
Cryptochiton stelleri
Gumboot chiton
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•  Phylum Arthropoda: jointed leg . 1 million species!
(most numerous phylum). Includes the insects. Very
successful phylum in terms of diversity of species and
habitats they live in. They have an exoskeleton of
chitin, and the molt their skeleton periodically (like
snakes). Subphylum Crustacea: 35,000 species, Includes the
copepods, crabs, lobsters, krill, and barnacles. •  Bilateral symmetry
•  Segmented bodies. Paired appendages (jointed legs).
Dorsal (on the back) heart, and ventral (on the stomach)
nerve cord. They (crustaceans) have a simple brain, and
an open circulatory system.
•  Exoskeleton of chitin which they molt
•  Some are planktonic (like copepods) while others are
benthic scavengers and predators (like shrimp and
lobsters), and still others are filter feeders (like copepods).
•  They (crustaceans) have separate sexes. Male transfers
sperm to female, and she holds the eggs. They have a
planktonic nauplius larvae
•  Class Copepoda (oar foot): copepods. Small and
planktonic. Major consumers of phytoplankton (mostly
diatoms).
•  Class Amphipoda(Malacostraca) (double feet):
sand fleas, caprellids (you ll see these later in our
float lab), whale lice, and the little organisms that
gray whales feed on are amphipods. They can
occur in great numbers. Many (like the ones gray
whales eat) are benthic and live in soft sediment.
Laterally compressed bodies.
•  Class Decapoda (Malacostraca) (10 feet). Largest class.
Crabs, shrimp and lobsters. All (even crabs) have a tail
like in the lobster. In the crab it is curled under. You can
use it to sex a crab (in the male it is thin while in the
female it is wide). Crabs have a high diversity of forms.
Decapods are an important food source for humans.
•  Class Cirripedia (Maxillipoda)(curled feet):
barnacles. Sessile and hermaphroditic. They
have the longest penis relative to body size of any
animal on earth (over 6 times their body length!).
Sessile, filter feed with their feet.
•  Class Isopoda (Malacostraca) (equal feet): Pill bugs
(terrestrial) and kelp isopods are examples of this class.
Some are parasitic on fish gills. Others can be seen just
above the high tide mark running like big pill bugs with
large feet (they are actually marine – species ligia).
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Copepoda
Isopoda
Amphipoda
Cirripedia: barnacles
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Echinoderms - spiny skin
Phylum Echinodermata
•  ~ 6,000 species living from the intertidal to the very deep sea
•  Deuterostomes: Formation of the mouth
second in deuterostomes evolutionarily
links echinoderms, hemichordates, and
chordates. Primitive echinoderms and
pterobranch hemichordates probably arose
from an ancestral tentacled filter-feeder,
which also gave rise to the chordate line.
Phylum Echinodermata
•  Class Asteroidea (star-like): Sea stars (starfish).
About 1600 species. Some have as many as 50
arms! Stomach sticks out from body for external
digestion. They can stick this stomach into a
bivalve (clam) shell and begin digesting it!
•  Class Echinoidea (hedgehog like). Sea urchins and
sand dollars, about 900 species. Very much like sea
stars (in terms of body organization), but have no
arms . In some urchins, the mouth (Aristotle s
lantern), is adapted for grazing on algae. Sand
dollars live in soft sediment and filter feed with tube
feet and move with their spines (opposite from other
echinoderms).
•  Radial pentamerous (5 part) symmetry as adults
•  Bilateral symmetry as larvae •  3 body cavities (coelomic cavities). –  Water vascular system: tube feet
–  Pedicellaria •  Endoskeleton (CaCo3) •  Poor or absent circulatory system. •  Non-segmented
•  Most are benthic as adults: filter feeders, grazers, scavengers,
detritivores, predators •  Most have separate sexes - broadcast and brood
Phylum Echinodermata
•  Class Ophiuroidea (snake form). Brittle stars and
basket stars, about 2000 species. Their arms an
wave and move like a snake. They use them for
movement and filter feeding (the tube feet do the
actual feeding).
•  Class Holothuroidea. Sea cucumbers. These lack
actual spines, but have soft spiny projections. Many
are eaten (there is quite a large fishery for them).
There are about 1,100 species, and some are found
very deep. They are filter feeders and deposit
feeders (literally eat the mud or sand and digest
organic matter out of it).
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Figure 33.37 Anatomy of a sea star
Asterioda: sea stars
Figure 33.36x3 Sea cucumber
Phylum Chordata
• notochord –flexible rod support between
nerve cord and gut
• Dorsal hollow nerve cord – forms from
the ectoderm and rolls into a tube – dorsal
to the notochord
• Pharyngeal slits – small opening at end of
gut or pharynx (nearest to mouth). • Muscular tail projecting beyond (posterior
to) the anus 14
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Figure 33.x4 Salp Chain
Phylum Chordata
Phylum Chordata
Other characteristics:
•bilateral symmetry
•Segmentation •three germ layers and a welldeveloped coelom.
•ventral heart, with dorsal and
ventral blood vessels and a closed
circulatory system
•complete digestive system •bony or cartilaginous endoskeleton
usually present
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Urochordata
SP Urohordata: tunicates,
larvaceans, salps
•Cellulose tunic
•Mouth opens to a basket-like
pharynx
•Pharyngeal gill slits
•Free swimming larval form
S.P Urochordata
S.P Urochordata
• Class Ascidiacea
tunicates
Class Thaliacea salps
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S.P Urochordata
Larvacean
Class Larvacea larvaceans
Phylum Chordata - Subphylum Urochordata
Clavelina huntsmani,
Didemnum carnulentum,
Styela montereyensis
Colonial tunicate,
Stalked tunicate
Light bulb tunicate,
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