Animal Diversity (1 &)
2
Multicellular, eukaryotic, heterotrophic organisms
that feed by INGESTION
Body symmetry
Radial symmetry
Bilateral symmetry
Bilateral symmetry
Dorsal
Anterior
Posterior
Ventral
Tissue organization
2 tissue layers =
Radially symmetric
3 tissue layers =
Bilaterally
symmetric
Two tissue layers:
Endoderm and Ectoderm
Ectoderm
Endoderm
Gut
Ectoderm
Endoderm
Gut
Ex: Hydra
Three tissue layers:
Ectoderm, Mesoderm,
Endoderm
Ectoderm: External Layer
Skin cells of epidermis
Neurons of brain
Mesoderm: Middle
Layer
Endoderm: Internal Layer
Lung (Alveolar) cells
Thyroid cells
Pancreatic cells
Cardiac muscle, Skeletal
muscle,Kidney cells,
Red blood cells,
Smooth muscle in gut
Body cavity
Acoelomate
Pseudocoelomate
Eucoelomate
Other characteristics:
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Openings into digestive tract:
One opening or tube within a tube?
Open vs. closed circulatory system
Organs for gas exchange
Organs for excretion
Endoskeleton, exoskeleton, hydrostatic skeleton?
Segmentation
Porifera
(i.e. sponges)
Cnidaria
(e.g. Hydra, sea anemones, jellyfish)
2 tissue layers
Platyhelminthes (Flatworms)
3 tissue layers
Acoelomate
unsegmented
No internal organs = must be flat to allow O2 and
nutrients in via diffusion
Most are parasitic – Schistosomiasis is a disease
caused by these guys. Tapeworm too.
Annelida
(Clamworms and earthworms)
Segmentation! Organs! They’re hydrostatic!
Annelida (Clamworms and
earthworms)
Mollusca
More than 85,000 species!
Characteristics of most molluscs:
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Hard external shell for protection
Mantle (excretes shell)
Visceral mass
Muscular foot for locomotion
Snail radula!
Ex: cuttlefish
Basic bivalve anatomy
Adductor muscles are welldeveloped in scallops because
they’re active swimmers. (They’re
also tasty)
Onwards! …to Ecdysozoa = molting animals
(Nematoda and Arthropoda)
Body covering =
cuticle
= exoskeleton
Nematoda
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Most abundant animal on Earth
Pseudocoelomate
Up to a million different species (only like 50k described)
15,000 species are described as parasitic
Sheds proteinaceous cuticle
LOTS of investment in reproductive organs
Arthropoda
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Animals with exoskeleton, segmented body,
and jointed appendages
Exoskeleton is periodically shed
Four subphyla: Cheliceriformes, Myriapoda,
Crustacea, Hexapoda
Exoskeleton is mainly chitin
First organisms to fly – unoccupied niche (air)
allowed for massive radiation
Cheliceriformes
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No antennae, no jaws
Pincer-like appendages called chelicera used
for grasping and fragmenting food
Myriapoda
Millipedes
2 pairs of legs per segment
Detritivores
Centipedes
1 pair of legs per segment
Predators
Crustacea
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Biramous (two-parted) limbs (even barnacles)
Most are free-living aquatic animals
Some (e.g. pill bugs) are terrestrial
Some (e.g. barnacles) are sessile
Ex: Crustacean claws
branch into 2 segments
Hexapoda:
Six-legged arthropods
External insect anatomy
3 distinct body units: head, thorax, and
abdomen
Insect head:
Search for: compound
eyes, ocelli, antennae,
labrum, mouthparts
Insect mouthparts:
Mandible, maxilla, labium
Evolution of mouthpart
morphology
Chewing mouthparts
(e.g. grasshopper)
A: Chewing
B: Lapping (e.g. bee)
C: Siphoning (e.g. moth)
D: Sucking (e.g. mosquito)
Arthropod respiration:
Tracheal system
Final notes:
No labs next week.
Then only two more labs:
- Animal Diversity 3 (chordates and starfish)
- and then a final lab practical
(no lecture for the last lab)
I will post a study guide this week on thinkbiologically.com
Don’t forget to turn in your reports!
Lots to do today! Have fun!