Animal body plans I Animal body plans
• A body plan is a set of fundamental traits - a basic structural blueprint - shared among a vast number of related organisms.
• There is a limited range of body plans among all living animals (between 30 and 35)
• Morphological differences between body plans are known as disparity (compare to diversity) Crown groups and stem groups
http://burgess-shale.rom.on.ca/en/science/origin/01-life-tree.php
Lines of Evidence
• Fossil record • Comparative morphology • Comparative genomics • “Evo-Devo” • Hox genes Evolution of Animals Multicellularity and origins
Digestive cavity
Reproductive Somatic cells cells
3 1 2 4 5 Early colony Gastrula-like Hollow sphere Beginning Infolding of protists; “protoanimal” (shown in of cell (cross section) aggregate of (cross section) cross section) specialization identical cells (cross section)
What is an animal?
• Multicellular • Motility • Aerobic respiration • Heterotrophs • Ingest food before digesting • Neurons (except sponges) • Muscle cells (except sponges)
7 What is an Animal? HAPLOID Sperm Eggs 1 2 • Most are diploid 7 Adult
except for haploid Digestive eggs and sperm tract Zygote (fertilized egg) Animals proceed • DIPLOID 3 through a well- Larva 6 Outer cell layer defined life cycle (ectoderm) includes embryonic Inner cell layer Blastula • (endoderm) (cross section) development Opening 4 5 Later gastrula (cross section) Early gastrula (cross section) 8 Choanoflagellates Fungi Porifera (Sponges) Major animal Animalia multicellularity Ctenophora phyla
Cnidaria
diploblasty Acoels LOPHOTROCHOZOAN Rotifera Loss of coelom Platyhelminthes triploblasty Segmentation Annelida Protostome development PROTOSTOMES Mollusca BILATERA ECDYSOZOA Nematoda
Cephalization, CNS, coelom Arthropoda Segmentation DEUTEROSTOMES Echinodermata Radial symmetry (adults) DEUTEROSTOMES Deuterostome development Chordata Segmentation Freeman 2014 Evolutionary innovations in animals
• Type of symmetry • Number of openings • Tissue complexity and organization • Type of coelom • Segmentation • Type of developmental pathways
10 Symmetry
Bilateral symmetry
11 Number of openings
12 Tissue complexity
• Diploblastic versus triploblastic Tissue complexity
• Embryonic cells give rise to primary tissue layers • ectoderm • endoderm • mesoderm Body covering (from ectoderm)
Tissue- filled region (from mesoderm)
Digestive tract (from endoderm)
14 Type of coelom: Acoelomate Animals
• Simplest Organ systems
epidermis gut cavity
no body cavity; region between gut and body wall packed with organs
15 Development of a coelom
Ectoderm Mesoderm
Endoderm
16 Type of coelom: Pseudocoelomate animals
• A “false coelom”, body cavity without a peritoneum epidermis gut cavity
unlined body cavity (pseudocoel) around gut 17 Type of coelom: Coelomate animals
• A true coelom – the body cavity has a unique tissue lining called a peritoneum
Ectoderm
Mesentery Peritoneum Endoderm Coelom
Mesoderm
18 The peritoneum encloses organs
• ……. and holds these organs in place.
gut cavity epidermis
peritoneum lined body cavity (coelom); lining also holds internal organs in place
19 Segmentation
Annelids: “ringed forms”
20 Development Sponges
• Multicellular • No tissues or organs • No head or mouth
22 Sponges
• No symmetry • No tissues or organs • Cell layers are loose federations of cells • Suspension feeders • Sexual and asexual
23 Diversity of sponges
24 Reproduction Ctenophora (comb jellies)
• Multicellular • No tissues or organs • No head or mouth • Comb
26 Comb Jellies Cnidaria
• Radial symmetry • Two true tissue layers (ectoderm and endoderm) • Sac body plan Cnidarians - jellyfish Cnidarians
• 3 Classes • Jellyfish
• Sea anemones, corals
• Hydra
Cnidarian Body Plans & Life cycle
Tissue layers: Epidermis Gastrodermis
31 Cnidarian Nematocysts
32 Cnidarians - corals
33