Transcript Invertebrate Phylum`s

Invertebrate
Phylum's
Invertebrate Basics:
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Animals with no backbones
Multi-cellular, cells have no cell walls
Most can move
Most have symmetry, meaning that if cut in
half the two sides will look about the same.
• Consumers, meaning they cannot make
their own food.
Main Groups
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Porifera=Sponges
Cnidaria=Anemone, coral & jellyfish
Arthropod=Insects, spiders, crustraceans
Platyhelminthes=Flat worms
Nematoda=Round worms
Annelida=segmented worms
Mollusca=Clams, octopus, squid
Echinodermata=Star fish, sand dollars, sea
cucumbers
Phylum Porifera
• Sponges
– Characteristics:
• Sessile, they are attached to a solid surface underwater.
• Most live in salt water, although some live in fresh water.
• diploblastic; that is, the body wall is made of two layers of cells with
a jellylike mesoglea between them;
• The body wall is perforated with pores (hence the name Porifera)
through which water containing food particles is filtered. The water
is drawn in through the pores by collar cells like those found in
choanoflagellates. (Some sponges can process a volume of water
more than 100,000 times their own volume in the course of a day!)
• dispersed by small, free-swimming larvae;
• about 10,000 species known
• No definite symmetry
• Simplest invertebrate with no nervous system
Phylum Cnidarians
• Jellyfish, Sea Anemones, Corals
– Characteristics:
• two layers of cells — ectoderm and endoderm — with a
jellylike mesoglea between them
• predominantly radial symmetry: body parts (e.g., tentacles)
arranged in whorls.
• cnidoblasts: specialized cells that secrete a stinging
capsule called a nematocyst.
• Food is taken through a mouth into the gastrovascular
cavity. There is no anus.
• Sexual reproduction produces a free-swimming, ciliated
larva called a planula.
• The phylum contains about 10,000 species distributed in 3
classes
Phylum
Platyhelminthes
• Flatworms (Planarian, Flat Worms, Turbellarians)
– Characteristics:
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This phylum contains some 20,000 species
Flattened body
bilaterally symmetrical body.
They have three embryonic layers (triploblastic): the
endoderm, the mesoderm, and the ectoderm.
Flat worms have no other body cavity than the digestive cavity
(acoelomates).
Asexual reproduction occurs through fragmentation or fission.
Flat worms have one digestive opening that branches to all
parts of the body. Turbellarians have a muscular pharynx to
up food.
Parasitic classes rely on the host for digestion.
They have a blind gut, meaning they have a mouth, but no
anus.
Phylum Annelida
• Examples: Annelids (Earthworms, clam
worm, leeches)
– Characteristics:
• segmented; that is, their body is made up of
repeating units.
• Has a nervous system
• There are about 12,000 species known
• Bilaterally symmetrical and vermiform.
• Body has more than two cell layers, tissues
and organs.
• Body possesses a gut, mouth, and anus.
• Has a true closed circulatory system.
• Has no true respiratory organs.
• Reproduces sexual, gonochoristic, or
hermaphoditic.
• Feed on a wide range of material.
• Live in most environments.
Phylum Mollusca
• Examples: Mollusks (clams,
mussels, oysters, scallops,
snails, slugs, octopus, squid,
chambered nautilus, tooth shells,
chitons)
– Characteristics:
• Over 70,000 living species
• 6 classes—Bivalvia, gastropoda,
cephalopoda, scaphopoda,
Amphineura, and Monoplacophora
• Bilaterally symmetrical
• Body is in 2 sections, the head-foot and
the visceral lump
• They have a closed circulatory system
with a heart
Phylum Nematoda
• Examples: Roundworms
(Hookworms, Pin worms, filarial
worms, guinea worm)
– Characteristics:
• A one-way digestive tract running
from mouth to anus.
• A cavity between the digestive
tract and the body wall.
• Some 25,000 species have been
identified but this may be less than
10% of the true number.
• Most are free-living; found in soil
where they are important
decomposers.
• Most are small although one that
lives in whales can reach 30 feet!
Phylum Arthropoda
• Examples: Insects, Arachnida, Scorpions, Spiders,
Crustaceans, Horseshoe Crabs, Centipedes,
millipedes, Shrimp
– Characteristics:
• Incredible diversity. Over a million living species have
been identified so far — more than all the other
species of living things put together — and this is
probably only a fraction of them, they make up 80% of
all described living things..
• Live in every possible habitat: fresh water, salt water,
soil, even in the most forbidding regions of Antarctica
and high mountains.
• A jointed external skeleton
• Segmented.
• Pairs of jointed appendages (legs); one pair to a
segment — used for locomotion, feeding, sensation,
weaponry.
• Bilateral symmetry.
• Main nerve cord runs along the ventral side.
• They molt, or shed their skeleton
Phylum
Echinodermata
• Examples: Starfish, sea
urchins, brittle stars, sand
dollars, sea cucumbers, sea
daisies
– Characteristics:
• Five rayed symmetrical body
• Radial symmetry
• Body has two layers of cells,
tissues, and organs
• A water vascular system that
moves its tentacles
• Open circulatory system