More Animals!
Sponges and Cnidarians
• Sponges- body is hollow tube with one
opening and many small pores. No tissues,
organs.
• Cnidarians- invertebrates that include corals,
sea anemones, jellyfish, hydras, and
portuguese man of wars. Live in salt water,
radial symmetry.
– most have tentacles with stinging cells to help
capture food
Worms
• Flatworms- usually parasites.
– Planarians- feed on small or dead organisms
– Flukes- parasites that can cause schistosomiasis, a
blood disease in humans
– Tapeworm- parasites that live in intestines of host
animal
• Roundworms- also called nematodes. Extremely
abundant, live in a variety of environments. Many
are parasites, some beneficial because they kill
pests
Mollusks
• Soft bodied invertebrates with bilateral
symmetry.
• Have open circulatory system that moves
blood through vessels and into open spaces
around organs
• Classified into
– Gastropods
– Bivalves
– cephalopods
Segmented Worms
• Annelids- have setae (bristlelike structures) to
hold onto soil to move.
• Earthworms- more than 100 segments, move
using setae.
• Marine worms- have segments with setae in
bundles
• Leeches- no setae. Feed on blood of animals
Arthropods
• Have jointed appendages, bilateral symmetry,
segmented bodies, an exoskeleton, a body
cavity, digestive system with two openings,
and nervous system
• Exoskeleton- hard, thick outer covering that
covers, supports, and protects arthropod,
– Molting- when the exoskeleton is shed and
replaced occasionally
Insects
• Three body regions
– Head- has pair of
antennae, eyes, and mouth
– Thorax- has three pairs of
legs, where wings attach (if
the insect has them)
– Abdomen- contains
reproductive structures,
open circulatory system.
• Obtain air and release
waste gas through
openings called spiracles
Metamorphosis
• Series of body changes as insects become
adults
– Incomplete metamorphosis- egg, nymph, adult
– Complete metamorphosis- egg, larva, pupa, adult
Arachnids
• Spiders and ticks
• Have two body regions (cephalothorax and
abdomen), four pairs of legs, and no antennae
The “Pedes”
• Centipedes
• Millipedes
• Have long bodies with many segments, many
legs, antennae, and simple eyes
Crustaceans
• crabs, shrimp, barnacles
• One or two pairs of antennae and mandibles
for crushing food
Echinoderms (eee-kye-no-derms)
• Have hard skeleton covered by a thin, bumpy or
spiny epidermis.
• Radially symmetrical with no head or brain
• Have water vascular system, a network of waterfilled canals connected to thousands of tube feet.
• About 6000 species
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Sea stars
Brittle stars
Sea urchins
Sea cucumbers