Transcript Porifera - sponges

Phylum Mollusca
• Includes over 100,000 species with
great variety in appearance and
structure
• include snails, slugs, oysters, clams,
octopuses, squid, etc.
• most have soft bodies protected by a
internal or external shell
• most have bilateral symmetry
• the body plan of mollusks have four
parts: a muscular foot, a mantle,
shell and visceral mass
• foot - used for
locomotion, very
muscular; used for
crawling, burrowing
or capturing prey
• mantle - soft outer
layer of body that
drapes over animal
• mantle produces the shell, functions in respiration,
waste disposal, and sensory reception
• mantle cavity houses a gill which extracts oxygen from
the water and disposes of fluid wastes
• radula - extends from the mouth and scrapes up food
• visceral mass- contains most of the internal organs
• true coelom houses the heart, reproductive organs, and part of
kidney
• organ systems include digestive tract, circulatory system, and
nervous system
The three most diverse groups of mollusks include:
1) gastropods
2) bivalves
3) cephalopods
Gastropods
• largest group including
snails, slugs, and conchs
• shell-less or single-shelled
mollusks that move by using
a muscular foot located on
the ventral side piece shells
• may live in fresh water, salt
water, or on land (mantle
cavity evolved into a lung
instead of a gill)
Bivalves
• include clams, oysters,
mussels, and scallops
• have two shells(valves)
held together by a
powerful muscles (1 or 2)
• most are sedentary or
sessile, but some may
move quickly by clapping
its valves together and
squirting water
• muscular foot is used for
digging and anchoring
Cephalopods
• include squids, octopi, nautiluses, and
cuttlefishes
• soft-bodied mollusks in which the head is
attached to a single foot; the foot is divided
into tentacles or arms
• most complex of the mollusks; built for
speed and agility
• have external shells(nautilus), internal
shells(squid), or no shells(octopus)
• well developed sense organs and large
brains; some have been trained
Ecology of Mollusks
• symbiotic relationships with algae and
parasites
• environmental monitors- filter water and are
used as pollution monitors
• subject of research because they never
develop cancer
Phylum Arthropoda
• over 1,000,000 types of segmented animals
• considered to be the most successful phylum
of animals that have ever existed
• include crayfish, lobsters, crabs, barnacles,
spiders, ticks, and insects
• all have jointed appendages (Greek arthron
means joint) such as legs and antennae
• all have hard exoskeleton (made of chitin)
for protection and support; must shed
exoskeleton (molt) to grow
• open circulatory system, complete digestive
system, nervous system, true coelom
(legs, antennae)
(Segmentation)
Body formed of
several distinct
segments:
cephalothorax fused head and
thorax segments
• head - sensory antennae, eyes, jointed
mouthparts
• thorax - 2 pincers & 4 pair of legs for walking
• abdomen - swimming appendages
Arthropods may be divided into 5 main groups
based on the number and structure of their body segments
and appendages (esp. mouthparts)
1) horseshoe crab considered a “living
fossil”
-only surviving member
of arthropods that were
abundant in the sea 300
million years ago
-gill bearing, marine
animals
2) arachnids - include scorpions,
spiders, ticks, and mites
- most live on land
- scorpions are nocturnal hunters,
carnivores, tip of tail bears a
poisonous stinger
- spiders are very diverse
group, active during the
daytime, spinnerets used
to spin complex webs; 4
pair of legs; complex
nervous system
- mite - (dustmite) - found in our homes
• thousands may be
found in a few square
centimeters of carpet
or in one dustball
• do not cause disease,
but may cause
allergies
3) Crustaceans - all
aquatic; include lobsters,
crayfish, crabs, shrimp,
and barnacles
• Barnacles are sessile marine crustaceans that
live in a shell; bottom-dwellers
• jointed appendages project from shell and
capture small food particles; no eyes, gills,
heart, or blood vessels
4) millipedes & centipedes - segments make
them look like annelids with paired legs on each
segment
Millipedes - wormlike
landlubbers, eat decaying
plants, 2 pair of legs on each
body segment
Centipedes - terrestrial
carnivores; 2 poison claws; 1
pair of long legs on each
body segment
5) Insects - represent 75%
of all known animal
species; over 1,000,000
species known; extremely
successful
• Most have three-part body: head, thorax, and
abdomen
• have sensory antennae, 2 eyes, several
mouthparts, 3 pair of legs, 1 or 2 pair of wings
• most go through metamorphosis - series of
changes during which young insects develop
into adults (changing shape and form)
Complete Metamorphosis
-Bees, moths,
butterflies
-Animals hatch into
larvae that look
nothing like adults
-Feed in completely
different ways
Molt several times then
change into a pupa
(stage in which body
completely
remodeled)
Incomplete Metamorphosis
• Chinch bug,
grasshoppers
• Immature forms look
like adults
• Nymphs lack sex
organs and other adult
structures
Insects and Humans (ecology)
Insects can be both beneficial and harmful
Harmful
• termites destroy
wood
• bees sting
• moths eat wool
• locusts eat crops
Beneficial
• pollination of crops
• honey
• silk
Echinoderms- “spiny-skinned”
• Echinoderms are coelomates, and are segmented
• examples include sea stars (starfishes), sea urchins, sand dollars,
sea cucumbers, and sea lilies.
• 6,000 species of echinoderms; they are all marine.
• echinoderm adults have radial symmetry, but they evolved from
ancestors that were bilaterally symmetrical
• free-swimming, bilaterally symmetrical larvae that metamorphose
(change as they mature) into radially symmetrical adults
• very simple nervous system to coordinate movement of arms (no
head or brain)
• most have spiny surface which comes from
extensions of its endoskeleton
• Gas exchange is done with numerous tiny
gills that extend from the surface of the
skin.
Echinoderms reproduce sexually and asexually
• sexual reproduction-sexes are separate and gametes are expelled
into the water.
• the gonads are large due to the necessity of releasing large
numbers of gametes into the marine environment
• fertilization occurs externally (in the water)
• asexual reproduction occurs if an
arm is cut off; the sea star can
regenerate its missing arm (ray)
• the fragmented piece can grow
back the rest of its body (as long
as part of the central disk is still
attached) through the process of
fragmentation
Spine
Cross Section
of Ray
Ampulla
Radial Canal
2 Stone Canal
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- Echinoderms use a water
vascular system for movement,
circulation and respiration
-consists of a water-filled ring
canal that branches into radial
canals & tube feet found in each
arm
• the ampulla is found on top of each
tube foot and helps force water
through the system which causes the
foot to extend
• each foot has a suction-cuplike end
used for movement and feeding
-Complete digestive
system includes a mouth
and an anus
- mouth located
centrally on its
undersurface
• Carnivorous - when eating a clam or oyster, it
grips the shell with its tube feet and positions
its mouth next to the opening between the two
valves of the shell
• the stomach pushes out through its mouth,
enters the mollusk, and digests the soft parts
- sea urchins and sand
dollars are sphere shaped
and have no arms
- spines are used for
protection and movement
- tube feet also used for
movement in the sea urchin
- tube feet in sand dollar do
not have suction cups and
are only used for
respiration
- solid, internal shell
Sea cucumbers - bilateral
symmetry, no arms, wimpy
endoskeleton made of
scattered calcium plates
- some have tentacles for
grabbing food
• Defense - shoots out long,
thin, sticky, poisonous
tubules from anus
• some will eject entire
digestive system and
regenerate it in a few days
Ecology of Echinoderms
• Echinoderms control population changes of other marine life
– Sea urchins control algae
– Sea stars hunt clams and coral
• crown-of-thorns (a sea star) feeds on only coral
• it has destroyed part of the Great Barrier Reef of
Australia- one of the largest reef systems in the world
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2 Stone Canal
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