Download 8- Phylum Echinodermata

Bio 200-Lab Lecture 10
Animal Diversity
I- Animal Characteristics:
Habitat: Place where an animal naturally lives.
Aquatic: in water, marine or fresh water.
Terrestrial: on land.
Amphibious: both terrestrial and aquatic.
Feeding Habits: Carnivores : feed on animals.
Herbivores: feed on plants.
Omnivores: feed on both plants and animals.
Filter Feeders: Filter food from water currents.
Parasites: Live in or on another organism.
Decomposers: Feed on decaying organisms.
Mobility: Sessile: doesn’t move, lives attached to a surface.
Sedentary: Not attached, but tends to be inactive.
Motile: moves about freely.
Symmetry:
Bilateral Symmetry:
Only one vertical plane passing through the midline divides the body of
the animal into 2 mirror-image halves.
e.g. humans, crayfish, fish, frogs….
Radial Symmetry:
Any plane passing through the central axis would divide the body into 2
mirror-image halves.
II-Animal Phyla:
1- Phylum Porifera:
- Most primitive animals
- 5000 sp. all aquatic, mostly marine
- Radial symmetry
- Adults: sessile
- 2 cell layers, but no tissues.
- Endoskeleton: spongin protein + spicules (calcareous or
siliceous)
- Filter feeders
2- Phylum Cnidaria:
Jellyfish, sea anemone, corals….
- Most are marine
- Radial symmetry
- Cells organized into tissues
- 2 body forms: Polyp : sessile
Medusa: motile
- 2 layers of cells separated by gelatinous material (mesoglea)
- Tentacles
- Mouth opens into a gastrovascular cavity.
- Carnivores
- Nematocysts: stinging cells on tentacles have coiled threads
released upon stimuli.
e.g. Portuguese man-of-war:
Marine colony of polyps (feeding, stinging, reproduction)
and medusas (floating).
e.g. Hydra: solitary F.W. polyp
e.g. Obelia: Colonial polyp
e.g. Jellyfish (2-40 cm in diameter): marine medusa
Moves by rhythmic undulation of the bell
e.g. Sea anemones and corals
Carnivorous marine polyps
Sea anemones can glide slowly along their foot (base)
Corals can precipitate minerals from sea water and
become encased in a hardened exoskeleton coral reefs
3- Phylum Platyhelminthes:
Flatworms
- Incomplete digestive system
- Tissues organized into organs
- Bilateral symmetry in adults
- Cephalization
- Representatives: Planaria: F.W., solitary
Flukes (liver, blood, lung flukes)
Tapeworms (intestinal parasites)
4- Phylum Nematoda:
Round worms
- Bilateral symmetry
- Tough thick cuticle protects body.
- Most are free-living, some are parasitic.
- Parasitic nematodes: e.g. ascaris (intestinal parasite).
5- Phylum Molluska:
- Soft-bodied, many have shells.
- Most are marine, few FW and terrestrial species.
- Predators, filter feeders, parasites or herbivores
- Basic Body Plan: - Muscular Foot
- Visceral mass
- Mantle : covers visceral mass and
secretes shell.
- Gills : Extract O2 and food from
water.
3 Classes:
1) Gastropoda: Snails and slugs
Single helical shell; slugs have no shells
2) Bivalves: Clams, oysters…
- 2 shells hinged together posteriorly.
- Most are filter feeders: water goes in through a siphon (incurrent)
passes to the gills where it is filtered, and leaves through another
siphon (excurrent)
3) Cephalopods: (octopus, squid, cuttlefish, nautilus…)
-Well developed heads and eyes
- Foot modified into tentacles with suction cups for grasping
prey
- All carnivores, all marine
- Highly motile: Expel water through a funnel to propel body.
- Shell: reduced in squids and cuttlefish, absent in octopus,
complex in nautilus
- Octopus and squid can change coloration, some discharge a
cloud of dark ink to elude the predators.
6- Phylum Annelida:
Segmented worms
- Marine, F.W, terrestrial
- Free-living or parasitic
- Complete digestive system
- Stiff bristles on body: help in locomotion and firm grasp on
substrate
e.g. earthworms, leeches (Parasitic or carnivores), marine
worms (Sand worm, feather duster worm)
-Sand worms have a pair of fleshy appendages on each
segment.
7-
Phylum Arthropoda:
1.1 M sp. : 85% of animals are arthropods
Most diverse and widely distributed phylum
Jointed appendages
Segmented body, bilateral symmetry
Exoskeleton made of chitin (thick or soft)
Molting : periodic shedding of the exoskeleton to allow for the
growth of the body.
- 4 classes
1) Class Insecta:
- 3 body parts: head, thorax, abdomen.
- 1 pair of antennae
- 3 pairs of legs
- 2 pairs of wings
2) Class Arachnida (spiders, scorpions, ticks and mites)
Carnivores: venomous bites or stings
3) Class Crustacea (lobsters, shrimps, crabs…)
- Mainly aquatic
- 2 pairs of antennae
4) Centipedes and millipedes
Centipedes: 1 pair of legs/segment; carnivores with
poison claws
Millipedes: 2 pairs of legs/segment; feed on decaying
plants
8- Phylum Echinodermata
- All marine
- 5 fold radial symmetry (Pentaradial symmetry)
- Endoskeleton with spines that usually project out of skin
- Locomotion: water vascular system with tube feet extending out
of body
1) Star-shaped echinoderms (Sea stars and brittle stars)
5 arms with a central disc.
Brittle star: flexible arms for locomotion
-Many sea stars are carnivorous (on bivalves)
- Can regenerate lost arms
2) Echinoids: (sea urchins, sand coins…)
- 5 rows of tube feet
- Most sea urchins feed on algae or dead animals,
some are poison-producing predators.
3) Sea cucumbers:
- No spines
- Sessile on ocean floor.
- Filter feeders with tentacles.
- Small skeletal elements buried in the body.
- Can eviscerate to escape predators.
9- Phylum Chordata:
Common characteristics:
1- hollow dorsal nerve cord
2- notochord
3- gill structures
4- postanal tail
- 2 groups of invertebrates (Lancelets and tunicates)
+ All vertebrates
5 groups of verebrates:
1) Jawed fishes
2 major classes
Cartilaginous fishes:
Sharks, skates, rays
- Skeleton made of cartilage
- Most are carnivores
- Continuous movement needed to move water past the gills
Bony Fishes:
- Largest and most diverse class of vertebrates
- Most are carnivores with teeth to hold the prey
- Operculum covering the gills should be moved to create
water currents across the gills
- Floating organ: swim bladder
2) Amphibians:
Frogs, toads and salamanders
- Double life: Terrestrial and aquatic
- Depend on water for reproduction
- External fertilization  aquatic tadpoles
- Most are carnivores
3) Reptiles:
- Completely independent from water.
- Amniotic eggs: Protective membranes
- Internal fertilization
- Dry scaly skin protects against dehydration
4) Birds:
- Feathers, wings, tail, scaly feet, beak.
- Wings: modifications of front limbs.
- Amniotic eggs, protected from dehydration.
- Low body weight: hollow thin bones
- Strong muscles
5) Mammals:
- All have fur or hair
- Nourish their young with milk form mammary glands
- In most sp. the young develops inside the uterus
- Exception: Duck-billed platypus, spiny anteater
- 2 main groups: Marsupials (koalas, kangaroos)
Placentals (most successful group)