Transcript chapter 7- Marine invertebrates-reg

Marine Invertebrates
Chapter 7
Invertebrates- no backbones
 97% of all animal species are invertebrate.
 Many are exclusively marine.
 All animals are:

heterotrophs

can reproduce sexually (many can
reproduce asexually as well)

motile at some point in their life cycle
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Phylum porifera- the sponges
 Sponges do not have specialized tissues,
but they do have specialized cells.
 Their body plan is asymmetrical.
 Adult sponges are sessile (attached to a
surface).
 Because of their lack of tissues and organs,
they can be separated through a strainer
and reform new sponges.
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Reforming of a
sponge
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Sponge Structure
 Ostia- numerous tiny pores that allow water
to enter.
 Suspension feeders- sponges filter plankton
and other food particles from seawater.
 Choanocytes- collar cells. Have flagella that
trap the food and create a current.
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Sponge Structure (cont’d)
 Osculum- opening where the water leaves
the sponge.
 Spicules and spongin- either silica or
calcareous that give the sponge support.
 Amebocytes- cells that move around and
produce spicules.
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Structure of a simple sponge
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A complex sponge
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Suspension vs. deposit feeding
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Reproduction in sponges
 Asexual- Branches or buds break off and
grow into new sponges- genetically
identical.
 Sexual- reproduce by broadcast spawning
of sperm.
 Eggs are usually protected in the sponge.
 Most sponges are hermaphrodites, but not
all.
 Sponge larva is the only motile stage.
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Sexual reproduction in sponges
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Fire Sponge
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Yellow Tube Sponge
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Green Rope Sponge
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Branching Tube Sponge
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Azure Vase Sponge
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Phylum Cnidaria- general info
 Radial Symmetry- several plains of
symmetry.
 Oral surface- mouth side.
 Aboral surface- opposite side.
 Tentacles- slender extension used for
capturing food.
 Nematocysts- stinging structures (inside
cells of tentacles)
 Mesoglea- the ‘jelly’ that fills the body.
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Body plans
 Polyp- tentacles on top, aboral surface
attached to a substrate

ex- sea anemone, coral
 Medusa- free swimming, tentacles on the
bottom. Classic jellyfish plan.
 Many cnidarians have both body plans in
their life cycle.
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Radial
symmetry
and body
plans in
Cnidarians
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Classes of Cnidarians
 Class Hydrozoa- often form colonies of
polyps, which reproduce by making small
medusas, or planula.

Siphonophores- free swimming
colonies that drift with the current.

some have floats for buoyancy.

Nematocysts produce very painful
toxins
 Ex- Portuguese Man-of-war, fire corals (not
true corals), Obelia sp.
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Hydrozoans have both polyp and medusa
stages in their life-cycles
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Body plan of
the
Portuguese
Man-of-war,
a
siphonophore
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Portuguese Man-of-war
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Portuguese Man-of-war on the beach
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Portuguese Man-of-war swimming
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Fire Coral
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Classes of Cnidarians
 Class Scyphozoa- large medusae.
Common jellyfish.
 Reproduce from a polyp which forms
many tiny ephyra- grow into medusae.
 Class Cubozoans- the box jellies. The
most lethal jellies in the world.

They are a favorite food of many sea
turtles.

The sea wasp can cause heart failure
in humans within minutes.
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Jellyfish- Class Scyphozoa
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Class Scyphozoa
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Class Scyphozoa
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Class Scyphozoa
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Sea Wasp- Class Cubozoa
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Class Cubozoa- Box Jelly
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Classes of Cnidarians- (cont’d)
 Class Anthozoa- polyps that can be solitary
or in colonies.

No medusa stage (most have a larva
called a planula)

most diverse group of cnidarians.
 ex- sea anemones, corals
 Corals secrete calcium carbonate skeletons.
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Octocoral
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Sea Anemone
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Giant Sea Anemone
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Biology of Cnidarians
 Organization- tissue level- no organs.
 Feeding and digestion- carnivores; use
nematocysts to sting and capture prey. .
 Behavior- no brain. Have a nerve net that
transmits impulses. Some have primitive
photoreceptors (‘eyes’).
 Respiration/circulation- all by diffusion
through the body surface. No circulatory
system.
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Corals and Symbiosis
 Zooxanthellae- dinoflagellates that live
inside coral polyps.

Provide nutrients for the coral.
 Coral Bleaching- occurs when temperatures
are too warm.

Zooxanthellae die, eventually killing the
coral.
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Coral Bleaching
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Phylum Ctenophora- Comb jellies
 Exclusively marine- only ~100 species.
 Have ciliary combs that allow it to move.

The combs often reflect light in a prism
effect.
 They are mostly pelagic, found in warm and
cold water.
 Radial symmetry
 Feed with sticky colloblast cells.
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www.imagequest3d.com
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Phylum Mollusca
 There are more species of Molluscs in the
ocean than any other animal group.
 Most have a soft body enclosed in a
calcareous shell.
 The body is covered by the mantle- a thin
layer of tissue that secretes the shell.
 A large muscular foot for locomotion.
 Some have a radula- a row of small teeth
that scrapes food off a surface.
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Classes of molluscs
 Class Gastropoda- Snails, abalones, limpets
and nudibranchs- approx 75,000 species.
 Have a coiled shell over a very large,
creeping foot.
 Use radula for scraping algae, but some are
carnivores
drill through the shells of other molluscs.
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Figure 7.19
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Tiger Cowrie
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Gastropod egg case
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Moon Snail- Class Gastropoda
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Figure 7.20
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Nudibranchs- sea slugs have bright coloration
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Sea Slug
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Class Bivalva- Clams, mussels, and
oysters
 Characterized by their two sided shells.
 No radula, no head. Have very strong
muscles for closing the shell.
 Filter feeders- use two siphons to draw a
current of water through the gills.
 Gills- dual purpose; used for gas exchange
as well as feeding.
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Class bivalva
 Burrowers- clams use their muscular foot to bury
themselves.
 Some attach to a substrate- mussels and
oysters cement themselves rocks or another
bivalve.
 Motile bivalves- scallops can swim by shooting
water out of the mantle cavity and by clapping its
shells.
 Pearl formation- some oysters secrete calcium
carbonate to coat an irritating particle in the
shell.
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Figure 7.22a
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Figure 7.22c
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Figure 7.22d
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Giant Clam
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Giant Clam
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Class Cephalopoda- ‘Head-footed’
Molluscs
 Octopus, squid, and cuttlefish.
 Mostly all agile swimmers, complex
nervous system.
 Muscular foot- modified into arms and
tentacles.
 Large, complex eyes- an octopus can see
complex images like we do!
 Most lack a shell- except the chambered
nautilus and chiton.
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Class Cephalopoda
 Cephalopods swim by forcing water out
the mantle cavity.
 Octopuses- commonly bottom dwellerslargest is the Pacific Giant (30ft.)

Good hunters- use beak-like jaws to
bite prey.

Use radula to scrape flesh, some
secrete paralyzing toxins.

Like many squid, they can secrete ink
to distract predators.
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Class Cephalopoda
 Squid-Elongated body and fins adapted for
swimming.

Reduced shell- a ‘pen’ made of chiton
that is embedded in its body for
support.
 Giant squid- can get 30-40 ft in length!
 Cuttlefish- have an internal shell
 Chambered Nautilus- external shell
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Figure 7.24a
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Figure 7.24b
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Figure 7.24c
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Chambered Nautilus
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Carribean Octopus
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Carribean Octopus
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Blue Ringed Octpus
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Pacific Giant (14ft)
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Carribean Squid
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First Photos of live Giant Squid
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First photos of a live Giant Squid
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Giant Squid
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Giant
Squid
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Biology of Molluscs
 Symmetry- bilateral
 Major characterisitcs- muscular foot, radula,
mantle (not found in all species)
 Feeding and digestion- radula, filter feeding
(bivalves) and complete digestive tract.
 Habitat- some are benthos, some are pelagic
(nekton)
 Respiratory system- gills
 Circulatory system- open in many molluscs,
some have closed circulation.
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Phylum Arthropoda
 Largest phylum of all animals- over a million
identified species.
 3 out of 4 animals on earth are arthropods.
 In marine environments, most of these are
classified in the Subphylum Crustacea.
 Ex- barnacles, shrimp and lobsters
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Basics of Arthropods
 Bilateral symmetry
 Segmented body- head, thorax, and
abdomen (or a cephalothorax- head thorax
combined)
 Exoskelton- non living external skeleton
made of chitin.
 Molting- must molt to grow.
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The molted exoskelton of
Galapagos shore crab.
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Subphylum Crustacea
 Most are marine.
 Specialized for life in the sea- most have
gills and appendages adapted for swimming
and other life functions.
 Chitinous exoskelton is reinforced by
calcium carbonate.
 Have two pair of antennae.
 ~ 68,000 identified species.
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Copepods- Very abundant in plankton.
Use large antennae for swimming.
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Barnaclesattach to a
surface.
They are filter
feeders.
Have feathery
feeding
appendages.
Favorite species
of Charles
Darwin!
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Amphipods- Small crustaceans that live in
seaweeds.
Beach hoppers live in beach debris.
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Isopods- have a more flattened body. Pill bugs
are the only common land species.
Marine species include sea roaches (but they are
not roaches).
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Decapods- ten legged crustaceans
 Shrimp, lobsters and crabs.
 Largest group of crustaceans.
 Five pairs of legs- the first pair adapted
with claws for feeding and defense.
 Many have swimmerets on the abdomen
to help them swim.
 Head and thorax fused into a
cephalothorax. Protected by a carapace.
 Distinct abdomen in many (except crabs)
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True crabs
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





Have a reduced abdomen.
It is small and concealed under the body.
Well developed carapace.
Males- abdomen is pointed
Females- u-shaped for carrying eggs.
Most are scavengers.
Some are terrestrial- returning to sea to lay
eggs.
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Coconut crab- adult and juvenile
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A View of
the
abdomens
of male
and female
crabs.
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Stages of Crustacean development
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Biology of Crustaceans
 Feeding and digestion- planktonic ones are
filter feeders.

Bottom dwellers have specialized parts
for food handling.
 Circulation- open circulation.
 Respiration- most use gills.
 Nervous system- small, simple brain.
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Other Marine Arthropods
 Class Merostomata- horseshoe crabs. 5
species alive today, very similar to species
extinct for millions of years.
 Sea spiders- not really spiders- they feed on
sea anemones.
 Class Insecta- extremely rare in the ocean.
Most ‘marine’ species live in seaweed debris
on the beach.
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Phylum Echinodermata
 Pentamerous radial symmetry- 5 planes of
symmetry as adults. Their larvae are
bilaterally symmetrical.
 Endoskelton- have an internal skeleton
consisting of calcareous plates covered by a
thin ‘spiny skin’.
 No head- have an oral and aboral surface.
 7000 identified species- all marine.
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Water vascular system
 A series of water filled canals.
 Used for locomotion when connected to the
tube feet.
 Also used for circulation of oxygen and
nutrient transport.
 Connected to the outside by the
madreporite, or sieve plate.
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Class Asteroidea- sea stars
 Five arms radiate from a central disc
 Oral side- has mouth and tube feet the
protrude from ambulacral grooves.
 Endoskeleton- interconnected calcium
carbonate plates make the arms flexible.
 Sea stars are predators of bivalves, snails,
barnacles and other slow moving animals.
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Aboral side of a sea star
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Oral side of a sea star
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Internal view of a sea star
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Class Crinoidea- Feather stars
and sea lilies
 Suspension feeders- use extended, feathery
arms to filter food from the water.
 Body plan- like an upside down brittle star.
 Arms are adapted into feathery feeders.
 Fossils date back to the Paleozoic era.
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Class Crinoidea- Sea Lilies
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Class Crinoidea- a Feather Star
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Class Ophiuroidea- Brittle Stars
 Also have ‘star shaped’ body.
 Very long, flexible arms
 Round central disk, and rapid, snake-like
movement.
 Use tube feet for feeding.
 Very diverse- over 2000 identified species.
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Class Ophiuroidea- Brittle Stars
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Class Echinoidea- sea urchins and sand
dollars
 Endoskeleton forms round, shell like
shape.
 Moveable spines aid in locomotion, with
tube feet in between.
 Unique mouth structure- jaws and muscles
called Aristotle’s Lantern for biting food.
 Sand dollars shortened spines and flat
bodies for living in soft sand.
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Class Echinoidea- Sea Urchin
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Class Echinoidea- Sand Dollars
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Class Holothuroidea- sea
cucumbers
 Look almost worm-like.
 No spines- lack obvious radial symmetry.
 Five rows of tube feet on one side for
locomotion.
 Have spicule-like bits of skeleton.
 Deposit feeders.
 Some secrete sticky toxins, others use
evisceration to ward off predators.
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Biology of Echinoderms
 Most are carnivorous- many evert part or all of
their stomach to digest outside the body.
 Have a central nerve ring- and nerve net similar to
cnidarians.
 Respiration and circulation- through body wall and
water vascular system.
 Separate sexes- reproduce sexually.
 Regeneration- dividing central disk into two can
result in two new individuals in sea stars, brittle
stars and some sea cucumbers.
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Figure 7.48b
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Figure 7.49
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