Annelida

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Phylum Mollusca "Next to Arthropoda, the
phylum Mollusca has the most named species in
the animal kingdom -- probably about 50,000
living species, not to mention some 35,000
fossil species discovered to date. The name
Mollusca indicates one of their distinctive
characteristics a soft body."
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Major Characteristics of Phylum Mollusca 1.
Body bilaterally symmetrical (bilateral asymmetry
in some) unsegmented, usually with definite
head 2. Ventral body wall specialized as a
muscular foot, variously modified but used
chiefly for locomotion 3. Soft Dorsal body
wall forms the mantle, which enclosesthe mantle
cavity, is modified into gills or a lung, and
secretes the shell (shell absent in some) 4.
Surface epithelium usually ciliated and bearing
mucous glands and sensory nerve endings
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5. Coelom mainly limited to area around heart
6. Complex digestive system rasping organ
(radula) usually present anus usually emptying
into mantle cavity 7. Open circulatory
system (mostly closed in cephalopods) of heart
(usually three-chambered), blood vessels, and
sinuses respiratory pigments in blood 8.
Gaseous exchange by gills, lung, mantle, or body
surface 9. One or two kidneys
(metanephridia) opening into the pericardial
cavity and usually emptying into the mantle
cavity
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10. Nervous system of paired ganglia, with nerve
cords and subepidermal plexus ganglia
centralized in nerve ring in gastropods and
cephalopods 11. Sensory organs of touch,
smell, taste, equilibrium, and vision (in
some) eyes highly developed in cephalopods
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Movement

• Foot acts as shovel wedge for clams or as slide
  for snails
• Squids octopuses move by taking in expelling
  water
• Oysters mussels are sessile as adults

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Digestive Tract

• 2 (two) opening tract
• Some are straight tubed
• Some are coiled in order to digest absorb more
  nutrients

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Nutritional Requirements

• Filter-feeders- sessile slow moving mollusks
• Herbivores snails eat algae
• Predators squids octopuses capture prey

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Nervous system

• Most have simple system lack sense organs
• Exception - OCTOPUSES HAVE COMPLEX NERVOUS SYSTEM
  (brain, eyes other sense organs)

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Reproduction

• All reproduce sexually
• Most have separate sexes
• Clams external fertilization
• Squid snails internal fertilization then
  deposit zygote

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Origin Diversity

• 100,000 species
• 2nd largest phylum
• Have coelom are protosomes
• Classified by
• Shell type
• Foot structure
• Internal body arrangement

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Classes of Mollusks
Class Gastropoda - "Stomach Foot" - The
gastropods are by far the most numerous and
diverse of the mollusks, including about 40,000
living and 15,000 fossil species. They are
usually sluggish, sedentary animals because most
of them have heavy shells and slow locomotor
organs. The shell is always of one piece and may
be coiled or uncoiled.
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Examples snails, limpets, slugs, whelks, sea
slugs
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Class Bivalvia - "Two Valves" - These are the
bivalved molluscs, most of which are sedentary
filter-feeders that depend on ciliary currents
produced by the gills to bring in food materials.
Unlike the gastropods, they have no head, no
radula, and very little cephalization.
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Examples mussels, clams, scallops, oysters,
shipworms
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Class Cephalopoda - "Head Foot" - The Cephalopoda
are the most complex of the molluscs. All are
marine, and all are active predators. They have a
modified foot that is concentrated in the head
region. It takes the form of a funnel for
expelling water from the mantle cavity. The
anterior margin of the head is drawn out into a
circle or crown of tentacles.
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Examples squids, octopi, nautiluses, cuttlefish
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Class Polyplacophora - Polyplacophores, or
chitons, are somewhat flattened and have a convex
dorsal surface that bears eight articulating limy
plates, or valves.
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Example chitons
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Biosphere Impact

• BENEFITS-
• Human food
• Huge role in food chains
• Monitor environmental conditions b/c they are
  filter feeders
• Sea slugs could be source of medicines

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• HARMFUL-
• Snails slugs consume crops
• Marine mollusks destroy wood boots docks
• Zebra Mussel introduced accidentally and has
  taken over the Great Lakes b/c they compete w/
  other species for food clog water intake pipes
  to treatment power plants

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PHYLUM Annelida

• Earthworms
• Leeches

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Reproduction

• Asexually regeneration

BUT usually sexually most are hermaphroditic
cant fertilize themselves
After being fertilized a cocoon is formed that
houses egg sperm
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Body Cavity

• Coelomate True cavity

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Segments

• yes

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Impact on Biosphere

• Fish food, birds food, frogs food snake food

Essential in plant growth b/c burrows allow water
air to penetrate
Increase nutrients for plants by breaking down
large organic matter
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Nutritional requirement how does it eat?

• In through pharnyx mouth

Crop storage
Gizzard grinds food
Intestine digests food

• Out through anus

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Nervous circulatory Systems

• Ganglia well developed into small brain with
  solid ventral nerve cord

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Where they live

• Polychaeta- Free or tube marine worms have
  parapodia for movement

• Oligochaeta terrestial

• Hirudinea leeches (no setae or
  parapodia) -freshwater o r moist tropical area

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Important Sturctures or lack of..

• Muscles run lengthwise around body for movement

• Receptors for light, temperature,
  moisture,vibrations, chemicals

• Nephridia rids waste from coelom to outside

• Setae- bristles for movement

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• Lack respiratory diffusion of gases in water
  only

Leeches have suckers on both ends for movement
Anterior end has teeth to hold on to host
Anesthetizing substance to numb
Secretes anticlotting chemical
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Arthropods

• Largest, most diverse most successful Phylum

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General Characteristics reasons for success

• Segmented bodies fused into regions (head, thorax
  abdomen)
• jointed specialized appendages
• exoskeleton composed of chitin
• complex muscular system
• ventral nerve cord brain ganaglia clusters

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• Open circulatory system
• Respiratory system (gills for marine arthropods
  or tracheal tubes/lungs for terrestrial
  arthropods)
• can have compound eyes, simple eyes or both
• complex life cycle -- Metamorphosis larvae
  different from adult

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Origin

• Trilobites
• now extinct
• no specialized legs
• good fossil records
• Arthropods now have fewer body parts
  specialized appendages

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Peripatus -- arthropod or annelid?

• Annelid -like -----segmented lacks exoskeleton
• Arthropod-like -----antennae, claws appendages
  (not jointed)

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Subphylum Crustaceans

• Typical example - lobster/crayfish
• cephalothorax - fused head chest w/ legs
  appendages attached
• abdomen - long narrow tail region

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Specialized Appendages

• Antennae
• mandible
• maxillae
• maxillipeds

• Claws
• walking legs
• swimmerets
• telson uropods

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Class Malacostraca - The class Malacostraca is
the largest class of Crustacea and shows great
diversity. The trunk usually has eight thoracic
and six abdominal somites, each with a pair of
appendages. There are many freshwater and marine
species.Examples Lobsters, crabs, crayfish,
shrimp
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Specialized Internal Structures

• Ventral nerve cord with swelled pairs of ganglia
  in each body segment
• Compound Eyes - on stalks to allow vision in any
  direction each moves independently
• Green gland - regulates salt liquid in blood

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Diversity

• Cerripods - barnacles
• copepods
• decapods - 10 legs
• isopods - same legs

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Subphylum CheliceratesGeneral Characteristics

• No sensory antennae
• simple eyes
• chelicerae - anterior appendage modified into
  pincers or fangs that can inject poison
• live in terrestrial environment

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Adaptations to terrestrial life water retention

• Malpighian tubules - excretory structure to
  remove metabolic waste return water to cells
• Exoskeleton
• book lungs - efficient gas exchange w/o excessive
  water loss

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Class Meristomata

• Horseshoe crabs - (NOT REALLY!)
• simple compound eyes
• no malpighian tubules
• have book gills -- precursor to book lungs?
• Eat solid food (clams worms,sft shelled clams,
  etc.)

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Class Merostomata - "Thigh Mouth" - Horseshoe
crabs are practically unchanged since the
Triassic period, some 225 million years ago. They
have an unsegmented, horseshoe-shaped carapace,
and a broad abdomen, which has a long spinelike
telson. On some of the abdominal appendages book
gills are exposed. Horseshow crabs can swim
awkwardly by means of their abdominal plates and
can walk on their walking legs. They feed at
night on worms and small molluscs and are
harmless to humans.
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Class ArachnidaGeneral Characteristics

• 6 pairs of specialized appendages
• 1 pr chelicerae - fangs
• 1 pr pedipalps - hold food sense organs
• 4 pr walking legs
• Absent or modified appendage on abdomen (ex
  spinnerets)

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• Most are terrestrial

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Order SpidersClassified by how the eat ..

• Hunters - strong legs excellent eyesight (2
  pair swivel 2 pair peripheral)
• Web Weavers - long slender legs, poor eyesight

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• All spiders produce silk for
• movement
• protection
• food wrap
• paralyze or kill w/ fangs secrete enzymes
  (poison) that digest liquefy prey

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Class Arachnida - Arachnids are a numerous and
diverse group, with over 50,000 species described
so far. The arachnid tagmata are a cephalothorax
and an abdomen, which may be distinct (as in
spiders) or nearly fused (as in ticks and
mites).Examples Spiders (35,000 species),
scorpions, ticks, mites
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Order Scorpions

• Long segmented abdomen w/ poisonous stinger
• pedipalps are large claws
• eats internal liquid of prey after crushing it
• nocturnal hide under rocks/ logs

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Order Mites Ticks

• Mites eat...
• plant cell contents
• dead skin cell
• bacteria in hair follicles

• Ticks
• parasite that need blood before it can molt

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Class Branchiopoda - Branchiopods have reduced
first antennae and second maxillae. Their legs
are flattened and leaflike and are the chief
respiratory organs. The most important and
successful order is the Cladocera, which often
forms a large segment of the freshwater
zooplankton.
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Subphylum UniramiansGeneral Characteristics

• Single pair of antennae
• unbranched appendages
• most numerous diverse group of organisms on
  Earth
• b/c of wide range of senses
• complex digestive system
• spiracles help respiratory system

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Origin

• Explosion of insects co-evolved with flowering
  plants
• Individual Insects evolved with certain plants
  (pollination)

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Diversity

• Class Chilopoda
• Centipedes
• 1 pr legs per seg
• carnivores w/ fanglike claws
• eat earthworms, insects snails _at_ night

• Class Diplopoda
• 2 pr legs per segment
• herbivores
• can be as long as 1/2 meter
• common in houses gardens

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Class Chilopoda - "Lip Feet" - Centipedes are
active predators with a preference for moist
places such as under logs or stones, where they
feed on earthworms, insects, etc. Their bodies
are somewhat flattened dorsoventrally and they
may contain from a few to 177 somites. Each
somite, except the one behind the head and the
last two, bears one pair of appendages.
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Class Diplopoda - "Two Feet" - Millipedes have
cylindrical bodies made up of 25 to 100 segments.
The four thoracic segments bear only one pair of
legs each, but the abdominal segments each have
two pairs. Millipedes are less active than
centipedes and are generally herbivorous, living
on decayed plant and animal matter and sometimes
living plants.
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Insects

• Class Insecta
• 3/4 of all known animal species are insects
• classified by structural differences (mouthparts
  of wings)
• Three distinct body regions
• 3 pr walking legs 3 pr mouthparts

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• Wings are folded extensions of the exoskeleton
  --- (0 wings to 1 pr to 2 pr)
• ability to fly gives insects advantage to escape
  predators, obtain food, migrate inhabit new
  environments

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Class Insecta - The insects are the most numerous
and diverse of all the groups of arthropods.
There are more species of insects than species in
all the other classes of animals combined!!
Insects differ from other arthropods in having
three pairs of legs and usually two pairs of
wings on the thoracic region of the body,
although some have one pair of wings, or none. In
size, insects range from less than 1 mm to 20 cm
in length, the majority being less than 2.5 cm
long. The insect tagmata are the head, thorax,
and abdomen. The head usually bears a pair of
relatively large compound eyes, a pair of
antennae, and usually three ocelli.
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Insect Metamorphosis

• INCOMPLETE - egg ,nymph , adult
• nymphs resemble adult but are very small, lack
  wings reproductive organs
• nymphs hatch from eggs molt repeatedly

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• COMPLETE - eggs, larvae, pupa in a cocoon, adult
• larvae are catepillars, grubs , maggots (etc.)
• they eat leaves decaying matter

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Insect adaptations

• Behavorial
• communication (flashes of light, sound,
  pheromones)
• social - for example, bees live in colonies
  each have specific jobs

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• Structural
• camouflage - to blend in with surrounding
  environment
• mimicry - to resemble other plants or animals

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an endoskeletal system made of a calcareous
network called stereom
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About its Body

• Spiny Skin -- External on the sea urchin
• Spiny Skin-- Internal on the sea star
• endoskeleton - made of calcium
• radial symmetry

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Water vascular system

• helps them move, obtain food exchange gases
• network of fluid filled tubules with only one
  opening for water to come in go out
• ring canal
• radial canals
• ampullae
• tube feet

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Reproduction

• Most can regenerate
• but all do sexual reproduction with external
  fertilization
• many larvae are bilateral (weird?????)

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Diversity

• Classified by whether the organism develops a
  mouth or anus first
• protostome - mouth first
• deuterostome - second mouth or anus first
• All echinoderms and chordates are deuterstomes

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Class Asteroidea

• Sea Stars (starfish)
• scavengers carnivores that feed on gastropods,
  bivalves, crustaceans polychaetes

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Class Ophiuroidea

• Brittle stars basket stars
• long, thin arms that make them more mobile that
  sea stars
• no suction cups on feet and no ampullae
• can filter feed in addition to being carnivorous

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Class Echinoidea

• Sea urchins and sand dollars
• Disc or sphere shape
• No arms
• Long poisonous spines in some
• Feed on sediment (some are grazers or scavengers

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Class Holothuroidea

• Sea cucumbers
• Five rows of tube feet run along body
• Eat plankton
• Can expel entire digestive system if threatened
  by predator (can be regenerated)

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Class Crinoidea

• Sea lilies and feather stars
• Oldest
• Sea lilies are sessile
• Feather stars can creep
• Mouth on dorsal surface (different from all other
  echinoderms)
• Eat plankton

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In the Biosphere

• Food Delicacies
• Potential source of new pharmaceuticals
• Sea urchins disrupt kelp sea weed population
• Crown of thorns sea star eats too much coral
  which can destroy the entire food chain for years

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Invertebrate Chordates

• Tunicates lancelets
• 4 common charateristics
• Dorsal hollow nerve cord
• Notochord
• Gill slits
• Post anal tail

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Tunicates

• Urochordates sea squirts
• Squirt sea water when disturbed
• Adults are sessile and filter feed
• Larvae are free-swimming
• As adults they lose all 4 common charateristics

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Lancelets

• Cephalochordates
• Retain all four characteristics as adults
• Can move but would rather bury themselves and
  filter feed