Animal Diversity I:
Invertebrates
BIO 101
Life Science
Dr. D. L. Daley
Animals
1. All are multicellular
2. Heterotrophic
3. Require oxygen
for aerobic respiration
4. Reproduce
sexually and sometimes asexually
5. Most animals
are motile during at least some phase of the life cycle
6. Life cycles
include embryonic development
What are
Invertebrates
w Animals without backbones
w Great diversity
w Examples
What are the
criteria for grouping animals?
w
Body symmetry
•
Radial
- body arranged around a central axis
•
Bilateral
- right & left body halves are mirror images
w
Type of gut
•
Incomplete
or complete
What are the
criteria for grouping animals?
w
Body cavities
•
Coelom - lined with peritoneum
•
Pseudocoelom - no peritoneal lining
•
No cavity
w
Segmentation
•
Repeating
series of body units - may or may not be similar to one another
Sponges
w
Phylum - Porifera
w
Aquatic - mostly marine
w
About 5000 known species
Sponges
w
Larvae - swimming
w
Adult - sessile
w
1mm to 2 meters tall
Cnidarians
w
Jellyfish, sea anemones and hydra
w
Mostly carnivorous - well armed predators
w
Mostly marine - 1 mm to 70 meters
Cnidarian Body Plan
w
Many change from polyp stage to medusa stage or vice
versa
w
Some are only polyps or medusae
w
Polyps
- cylindrical & attached to substratum
•
Sea
anemones, corals & hydras
w
Medusae - shaped like bells or umbrellas
•
Swim
by jet propulsion
•
Separate
sexes
Polyp Stage
Medusa Stage -
Jellyfish
Sea Anemones
Corals
Portuguese
Man-o-war
Phylum Nematoda
w
Roundworms
w
Bodies are long and round - bilaterally symmetric without appendages
w
Pseudocoel - under pressure - hydroskeleton
Nematodes
w Most are free-living and
harmless
w
Some are parasitic
•
Hookworm -
In southern US - Adults in intestine - Larval form must re-enter human by way
of skin
•
Filarial Worms - Live in lymphatic system & block vessels
s
Lymph vessels return excess tissue fluid to venous circulation
s
Blocked vessels cause fluids to accumulate in the peripheral tissues
s
This causes enlargement of affected appendages
s Elephantiasis
s Spread when mosquito feeds on
human blood & ingests larvae
Hookworm &
Pinworm
Elephantiasis
Mollusks
w
Most have a shell of calcium carbonate & protein
w
Many have fleshy foot - locomotion
w
Many have a radula - toothed tongue
used in scraping surfaces for food
Molluscan Diversity
w
Gastropods - largest class - snails and slugs
w
Chitons - slow-moving grazers -
dorsal shell with 8 plates
Molluscan Diversity
w
Bivalves - mollusks with two valves or shells
•
Filter
feeders
w
Cephalopods - active predators
•
Squids,
cuttlefish and octopuses
•
Expel
water through the funnel for locomotion
Annelids
w
Earthworms, polychaetes (some are predators
and some are tube dwelling filter feeders) and leeches
w
Bilateral symmetrical and segmented
Sedentary Marine
Worms
Earthworms
w
Body divided into segments
w
Scavengers - ingest moist soil that contains decomposing plant material
w Each worm can eat its own
weight every 24 hours
Earthworm
Leeches
Arthropods
w
Over a million species known
w
Hardened exoskeleton - must molt to grow
w
Jointed appendages - makes movement possible
w
Head, thorax & abdomen
Arthropods
w
Respiratory structures - gills in aquatic forms and tracheal system
(air conducting tubes) in land dwellers
w
Specialized sensory structures - eyes, sensory organs for hearing,
touch, smell and taste
Chelicerates
w
Spiders and their Kin
w
Marine living species - few mites, sea spiders and horseshoe crabs
w
On land - spiders, scorpions, ticks and chigger mites - arachnids
Chelicerates
Arachnids:
Scorpions & Spiders
w
Efficient predators
w Bites of ticks can spread bacterial agents
for lyme
disease and Rocky Mountain Spotted Fever
Spiders
Yellows Desert
Scorpion
Deer Tick and Mite
Crustaceans
w
Shrimps, lobster, crayfish, crabs, barnacles, pillbugs
and many others
w
Calcified exoskeleton
w
Most are marine & small
w
Two pairs of antennae - only arthropod with this
Shrimp and
Lobsters
Crabs
Barnacles
Pill Bug
Millipedes and
Centipedes
w
Millipedes - about 100 legs
w
Centipedes - between 15 & 177 legs
w
Millipedes - as they develop- body segments fuse such that each fused segments
has two pairs of legs
•
Scavengers
on decaying material
w
Centipedes - fast moving aggressive predators
•
Prey
on insects, earthworms and snails
Millipedes and
Centipedes
Insects
w
Over 800,000 species
w
Head, thorax & abdomen
w
Head - paired sensory antennae & paired mouthparts
•
Mouthparts
specialized in biting, sucking, sucking or puncturing
w
Thorax - three pairs of legs and two pairs of wings
Damselflies &
Dragonflies
Insect Life Cycles
w
Growth and molting - young insect is a miniature of the adult
•
Silverfish
w
Incomplete metamorphosis - gradual changes from juvenile to adult structures
(e.g. ap-pearance of wings & reproductive
structures)
•
True
bugs, grasshoppers & cockroach
Grasshopper and
Walking Stick
Insect Life cycles
w
Complete metamorphosis -
Hatch as larvae called caterpillars, maggots or grubs - after
several molts become pupa (chrysalis) - the winged adult develops
during pupation & emerges fully developed
•
Flies,
bees, butterflies & moths
Honeybees