MARE 171

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Marine Invertebrates
MARE 171
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Phylum Mollusca
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Phylum Mollusca

• 2nd largest phylum (110,000 spp)

• Body Plan
• Visceral Mass
• Mantle
• Foot

• Radula
• Nephridia nephrostome
• Gills

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Phylum Mollusca
Rudy, you're like school during summer
vacationYeah, no class. - Russell Cosby
Phylum Mollusca has Seven Classes
Class Polyplacophora - Chitons Class
Aplacophora - Mollusks without shells Class
Monoplacophora - Mollusks w/ one shell Class
Schapoda - Mollusks w/ a tubular shell Class
Gastropoda - Gastropods, snails their relatives
Class Bivalvia - Bivalves Class Cephalopoda -
Cephalopods, squids octopuses

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Class Polyplacophora
Phylum Mollusca
Chitons Exclusively Marine Have an external
shell w/ 8 overlapping plates They normally live
on rocks scrape algae w/ their radula (A
flexible tonguelike organ in certain mollusks,
having rows of horny teeth on surface) Because
the mantle secretes these 8 plates, chitons can
bend to fit their home
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Phylum Mollusca
Class Aplacophora
Exclusively Marine
Mollusks without shells -secretes calcareous
spicules or scales They usually resemble worms,
are found in deep water, often more than 3,000
m burrowers About 320 spp in this class, move
via cilia generally very small.
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Phylum Mollusca
Class Monoplacophora
Meaning having one shell, are a very small group
that has been known of for a short
time Originally thought to exist only in fossil
record, they were rediscovered in 1952, there
are now about 10 known spp, all of which are deep
ocean dwellers This class is characterized by
having an unhinged shell.
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Phylum Mollusca
Class Schapoda Tusk Shells
Exclusively Marine Have a tubular shell open at
both ends Are over 400 spp, they are usually
found in mud or sand with the posterior end
extending out This class is unusual because it
lacks both gills heart Gas exchange occurs in
the mantle blood is circulated by contractions
of the foot
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Phylum Mollusca
Class Gastropoda
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Phylum Mollusca
Class Gastropoda
Largest group of mollusks - 40,000 75,000
species These are also the only mollusks that
live on land Lack gills, use the mantle as a
makeshift lung for extracting oxygen and
breathing Most species have coiled shells, and
evolved tentacles and eyes Includes marine
animals like the sea slug and terrestrial animals
like the slug and snail
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Class Gastropoda
Phylum Mollusca

• Cone Shells
• powerful sting used to
• capture prey
• Some humans have been fatally wounded
• especially those that feed upon mollusks fishes
• at least 500 spp in world's warm waters
• Animal inside shell often w/ distinctive
  coloration

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Class Gastropoda
Phylum Mollusca

• Hawaiian limpet (Cellana sandwicensis)
• On boulders in high intertidal zone
• Has coarse ribs animal's foot is yellow
• Shell interior is light gray attains 2.5 in
• Cellana exarata has finer ribs, gray foot, dark
  gray interior
• Cellana talcosa attains 4 in interior is white
• All spp are endemic but rare in accessible areas
• Highly prized for food, but 5 annual drownings
  associated w/ fishing practices

• Limpets (opihi)

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Class Gastropoda
Phylum Mollusca

• Cowries
• animals' mantle is on outside
• secreting the shell from the top-down keeping
  it protected most other shells secreted from
  inside-out
• hence glossy interior of many shells
• remain hidden during day
• emerge at night to feed  
• Empty but intact shells are usually the result of
  predation by cone shells
• Algal or sponge grazers
• In Africa other countries, cowry shells were
  used as currency

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Class Gastropoda?Subclass Opisthobranchia
Phylum Mollusca

• Nudibranchs, Bubble Shells, Sea Hares
• Evolutionary process of abandoning shells in
  favor of chemical/biological defenses
• Opisthobranchs? gills behind,
• as gills are near anus
• Eggs are huge coiled masses
• Larvae begin w/out shells (trochophore)?develop
  into shelled larvae (veliger) which is
  planktonic?then settle lose their shell to form
  adult

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Phylum Mollusca
Class Bivalvia
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Phylum Mollusca
Class Bivalvia
Marine invertebrates w/ hinged shell divided into
2 halves The hinge is held together by a ligament
1 or 2 adductor muscles Live in sand or mud,
use their foot for digging anchoring to
surfaces Use the hinges to take in food, and are
also able to jet some distance away (scallops
file shells) by closing the hinged shell
squirting the water taken in out of the mantle
cavity Filter feeders, some have
zooxanthellae Some examples include clams,
oysters, scallops, mussels
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Class Bivalvia
Phylum Mollusca

• Pearl Oysters
• Blacklipped Pearl Oyster (Pinctada margaritifera
  )
• Uncommon in quiet bays shallow reefs
• Attached to reef at the hinge end w/ byssal
  threads NOT TRUE OYSTER
• Easily identified by the fringed opening of
  valves
• Produces high-quality pearls cultured
  extensively outside Hawaii
• Nearly exterminated locally at the beginning of
  the 1900's
• Illegal to collect

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Phylum Mollusca
Class Cephalopoda
Ah, Squiddy! I got nothing against ye. I just
heard there was gold in yer belly. Ha ha har, ha
ha ha har! - Sea Captain McCallister
Cephalopods a class of Mollusks that have an
elaborate nervous and muscular system are
carnivorous e.g. squid, octopods, cuttlefish,
nautilus
Squid
Octopus
Nautilus
Cuttlefish
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Phylum Mollusca
Class Cephalopoda

• modification of the mollusk foot
• muscular hydrostat, into the form of arms or
  tentacles
• Ejects ink defense

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Squid Movement Defense
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Class CephalopodaThe Squid and the Whale

• Discovery!
• First Giant Squid (Architeuthis)
  ever photographed LIVE
  (9/05)
• North Pacific Ocean in
  Japanese waters
• 25 ft long
• 2,950 ft (900 m) deep
• used baited fishing line

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Class CephalopodaThe Squid and the Whale

• Predators Sperm Whales
• Battles leave sucker marks on skin
• Cameras have been placed on sperm whales in hopes
  of seeing the squid

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Phylum Arthropoda
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Phylum Arthropoda
The most diverse phylum, largest geographical
distribution, most numbers Total population of
arthropods on Earth is estimated at around one
billion billion individuals (quintillion) -80
of all animal spp are arthropods Ancestry
morphology, embryology, indicate annelid
ancestry? not universally accepted Closest
Relatives morphological, embryological,
molecular studies indicate Phyla Tardigrada
Onychophora
velvet worms
waterbears
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Phylum Arthropoda

• Basic Body Plan
• Heteronomous metamerism segmentation in unequal
  sections? Head, thorax, abdomen
• Extensive fusion of segments w/ similar
  function?tagmata
• cephalothorax
• Each segment bears a pair of jointed appendages
• Wide adaptation of appendages for multiple
  functions
• Sensory (antennae), feeding (mandibles, maxillae,
  maxillipeds)
• Integument armor covering chitin protein to
  form exoskeleton
• Hardened via deposition of CaPO4 or CaCO3 salts

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Phylum Arthropoda
Phylum Arthropoda includes the following
divisions Subphylum Crustacea (The
crustaceans) Subphylum Hexapoda, (The
insects) Subphylum Myriapoda, (The millipedes
centipedes) Subphylum Cheliceraformes (The
horseshoe crabs arachnids) Class Trilobita
(extinct)
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Phylum Arthropoda
Subphylum Crustacea
Yar, I'm running a school for lobsters, we
practice tough love, daily chores etc. No?Okay,
I understand, it can be hard to let go. Tell me
this then ... do ye have any spare change? - Sea
Captain McCallister
Consisting mainly of aquatic species Crustaceans
have 2 or 3 tagmata have 2 pairs of antennae, a
pair of eyestalks w/ compound eyes, a pair of
mandibles on head, as well as a pair of legs on
each body segment These legs are biramous, or two
branches, meaning that each leg has a joint in
it All crustaceans respire via gills
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Phylum Arthropoda
Subphylum Crustacea
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Phylum Arthropoda
Subphylum Hexapoda
Largest class of animals on Earth, comprising of
at least three fourths the animals on the
planet Includes insects, springtails,
etc Characterized by having uniramous, or single
branched, appendages Majority of uniramians are
terrestrial, although a few species are aquatic,
very few marine
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Phylum Arthropoda
Subphylum Hexapoda
MARINE INSECTS Very rare only 250-350 spp Why?
Include spp of open ocean (pelagic), of tide
pools (those in intertidal zone), beach marsh
dwelling (those regularly exposed to salt water
from tides)
Maybe due to major competitors/predators
(crustaceans)

• Bledius spectabilis, Rove Beetle
• Burrows in intertidal zone
• ? very narrow openings at surface (lt 2 mm)? when
  covered by water, air pressure in the burrow
  keeps water out

• Halobates, Sea Skaters
• Dont dive
• Feed on zooplankton, dead jellyfish, fish eggs
• Lay eggs on floating debris

• Pontomyia, Marine Midge
• Skate on 2 legs (rare)
• ? Reduced wings, skate on ocean surface
• ? larval-like
• Adults live for few hours, die
• Larvae feed on detritus algae

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Phylum Arthropoda
Subphylum Myriapoda

• Millipedes Centipedes
• Class Diplopoda millipedes
• Long body w/ head trunk regions
• Trunk has 20-100 segments
• Each segment a tagmata of 2 segments ? 2
  appendages/segment
• Terrestrial, eat leaf litter
• Class Chilopoda centipedes
• Long flattened body, head trunk regions
• Trunk has 15-180 segments
• Each segment w/ 1 pair legs
• First pair of trunk appendages modified as poison
  claws
• Exclusively terrestrial carnivores, feed on
  insects

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Phylum Arthropoda
Subphylum Cheliceraformes
Nice doggy Milhouse Van Houten
Includes arachnids, horseshoe crabs numerous
other animals which have become
extinct ever since the Paleozoic era 2nd most
prominent group in arthropoda after uniramians
Classes Arachnida (spiders, ticks, scorpions)
Merostomata (horseshoe crabs) Chelicerae
preoral appendages modified as fangs or pincers 2
Tagmata cephalothorax abdomen
Predators, parasites, or decomposers
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I want your blood

• Horseshoe Crabs blood
  contains amoebocyte ?
  cells in blood that act as
  an immune system
• These cells bind to a
  pathogen and form a clot
  to physically
  quarantine the
  pathogen
• Pharmaceutical companies use an
  extract of the blood (LAL) to test that
  all finished products are pathogen-free
  before distribution to customers
• Respond to endotoxin secreted by marine
  bacteria

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Phylum Arthropoda
Class Trilobita
First appeared approximately 540 million years
ago Closest living relatives are horseshoe
crabs Believed to be first animals w/ color
vision Most were detritus feeders, although some
predatory Diverse common around 500 million
years ago Extinct 245 million years ago
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Phylum Bryozoa
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Phylum Bryozoa
Aquatic organisms, living in colonies A few to
many millions form one colony Some bryozoans
encrust rocky surfaces, shells, or algae Others
form lacy or fan-like colonies Bryozoan
colonies range from millimeters to meters
individuals 1 mm
lophophore
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Phylum Brachiopoda
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Phylum Brachiopoda
Marine animals that look like clams -not
closely related to molluscs Related to Bryozoa
Phoronida ? synapomorphy lophophore Common
in marine habitats cold or deep water About
300 living spp of brachiopods
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Phylum Phoronida
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Phylum Phoronida
One of the smallest least familiar phyla About
12 or so living species Horseshoe worms,"
locally abundant in sediments Elongated worm-
shaped, but gut loops ends close to mouth The
mouth is surrounded by the ciliated feeding
structure ? lophophore
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Phylum Echinodermata
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Phylum Echinodermata

• Largest phylum to lack any freshwater or land
  representatives
• Most are pentameral - have fivefold symmetry, w/
  rays or arms in fives or multiples of five?
  pentamerous radial symmetry
• Have a system of internal water-filled canals,
  which in many echinoderms form suckered "tube
  feet", w/ which animal may move or grip objects
• Include starfish, sand dollars, brittle stars,
  sea cucumbers, sea urchins

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Phylum Echinodermata
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Phylum Echinodermata

• Class Echinoidea sea urchins, sand dollars
• Class Asteroidea starfish
• Class Chronoidea sea lilies, feather stars
• Class Holothuroidea sea cucumbers
• Class Ophiuroidea brittle stars
• Class Concentricycloidea sea daisies

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Class Echinoidea
Sea urchins, heart urchins, sand dollars One of
the more diverse successful echinoderm
groups Roe (egg mass) of some spp resulting in a
commercial fishery Larval development of
echinoids has also been studied extensively,
many discoveries in developmental biology have
been made using echinoids Echinoids also have a
substantial fossil record
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Class Echinoidea

• Very efficient locomotory system
• hydraulic tube-feet?tubular pipes emerging from
  small hole called ambulacra, w/ vaccum attachment
  discs at end
• skeleton is a symmetrical structure made of
  close-fitting calcareous plates - which grow in a
  definite pattern, constantly adding more more
  plates, held together by flexible collagenous
  fibers ? test
• armed w/ thick spines, smaller
  spines ending w/ sharp
  sometimes
  poisonous pincers

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• Pedicellaria? 'three jawed forceps' called
  pedicellaria, which are used by the urchin to
  clean the epidermis and grasp food particles

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Class Asteroidea
True starfish have no sharp
demarcation between arms
central body, they move using
tube feet Most starfish are
predators, feeding on sessile or slow-moving prey
such as mollusks barnacles Many, but not all,
starfish are able to turn a portion of their
stomachs out through the mouth, thus digest
food outside of the body.
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Phylum Echinodermata
Class Asteroidea

• Sea Stars? Most Common

• Crown-of-Thorns (Acanthaster planci)
• Frequent at scuba depths feeding upon corals
  (usually Pocillopora meandrina)
• Appears fluorescent green at depth
• Spines are tipped w/ venom
• Natural predator Tritons Trumpet less
  frequently Harlequin shrimp
• Has not yet caused significant damage in HI

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Class Chronoidea
Stalked crinoids, or "sea lilies", lived attached
to the bottom, filtered food particles from
currents flowing past them Only attached
suspension-feeding echinoderms Important group
for studying the numerous extinct attached
suspension-feeding echinoderms Mostly inhabit
deep water not abundant Unstalked crinoid, or
"feather star" superficially resembles a
starfish, but the mouth faces up crawls by
"walking" on specialized cirri
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Class Holothuroidea

• Sea Cucumbers are generally long wormlike
• retain pentameral (five-rayed) symmetry, w/ five
  rows of tube feet running from the mouth along
  the body
• Surrounding mouth are 8 - 30 tentacles (modified
  tube feet)
• they are used for crawling along sea bed or
  anchoring to rock
• Retain the skeleton of echinoderms, but in most
  spp the skeletal plates are reduced to
  microscopic spicules
• Think of a holothurian is as a sea urchin that is
  lying on its side, stretched out, and missing
  much of its skeleton
• Common in the oceans of today also common in
  shallow-water habitats such as tidepools.

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Class Holothuroidea
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Class Ophiuroidea
Over 1600 spp - brittle stars basket stars
Brittle stars have long, flexible arms move
fairly rapidly by wriggling their arms Basket
stars larger arms are very highly forked,
branched, more flexible Most ophiuroids are
scavengers detritus feeders, although they also
prey on small live animals such as small
crustaceans worms
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Class Concentricycloidea
Sea Daisies - 2 species known All are lt1 cm
diameter Discovered in 1986 position w/in the
echinoderms has been contentious Disk-shaped
flattened body. Do not have mouthparts appear
to obtain nutrition through the membrane
surrounding their body Found in deep waters,
living upon decaying wood Single genus Xyloplax
2 spp, 1 Pacific 1Atlantic
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Species of the Day
Post-larval
Juvenile
Kona White Color Morph
Kona Black Color Morph

• Common Name Yellow Tang
• Scientific Name Zebrasoma flavescens
• Hawaiian Name Lau'ipala