Animals
Primary embryonic germ layers • Triploblastic: three germ layers Triploblastic gastrulation forms – Ectoderm: develops into epidermal & neural tissues three germ layers – Endoderm: develops into gut & accessory organs
– Mesoderm — displaces blastocoel: develops into muscle, ECTODERM MESODERM ENDODERM endoskeleton, & connective tissues • Epidermis of skin and its • Notochord • Epithelial lining of derivatives (including sweat • Endoskeletal system digestive tract glands, hair follicles) • Muscular system • Epithelial lining of • Epithelial lining of mouth • Muscular layer of respiratory system and rectum stomach, intestine, etc. • Lining of urethra, urinary • Sense receptors in • Excretory system bladder, and reproductive epidermis • Circulatory and lymphatic system • Cornea and lens of eye systems • Liver • Nervous system • Reproductive system • Pancreas Archenteron • Adrenal medulla (except germ cells) • Thymus • Tooth enamel • Dermis of skin • Thyroid and parathyroid • Epithelium or pineal and • Lining of body cavity glands pituitary glands • Adrenal cortex
Figure 47.16
Mesoderm Blastopore Figure 32.9b
Figure 40.5 Figure 40.5 Epithelial Tissue Connective Tissue • Continuous sheet or layers of cells Loose connective tissue Blood Collagenous Plasma with direct cell-cell junctions fiber Whit e • All three germ blood Apical cells layers start as surface 55 µ m epithelia, Basal Red blood 120 µ m Cartilage so epithelial surface Elastic cells Stratified fiber tissues may squamous Fibrous connective tissue Chondrocytes derive from epithelium any germ 100 µ m layer. Chondroitin sulfate
30 µ m • Cells are Pseudostratified Bone Adipose tissue Cuboidal ciliated Nuclei suspended in epithelium Columnar columnar Central epithelium Squamous epithelium canal Fat droplets extracellular epithelium matrix. Osteon 700 µ m 150 µ m • Derived from mesoderm.
Figure 40.5 Figure 40.5
Muscle Tissue Nervous Tissue Skeletal muscle
Nuclei Glia 15 µm Neurons Glia Muscle Neuron: fiber Dendrites Striation Cell body (Sarcomere) Axons of 100 µm Axon neurons
Smooth muscle Cardiac muscle 40 µ m Blood (Fluorescent LM) vessel (Confocal LM) • Specialized for contraction. • Specialized to conduct electrochemical nerve impulses. • Derived from Nucleus Muscle 25 µm Nucleus Intercalated 25 µm fibers disk mesoderm. • Derived from ectoderm.
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Major patterns of baupläne Bauplan: Ger. “Life Plan” (pl: baupläne) Diploblastic Ecdysozoa Lophotrochozoa Deuterostome The arrangement, pattern, and development of tissues, organs, and Protostome? systems unique to a particular type of organism. Triploblastic
• Cleavage • Blastulation • Gastrulation
(c) Acoelomate. flatworms Body covering Larval Development Coelom (from ectoderm) Tissue- filled region (from Protostomal development occurs in two distinct animal groups – Formation of body cavities mesoderm) allows movement of organs
• Lophotrochozoa: have ciliated larval stages within the body, esp. gut Digestive tract – Usually with a distinct larval stage called a trochophore expansion & motility (from endoderm) Apical tuft (b) of cilia Pseudocoelomate. nematode worm Body covering • Acoelomate: no body cavity (from ectoderm) • Ecdysozoa: have no ciliated tissues • Pseudocoelomate: cavity Muscle layer – All stages have a chitinous cuticle Pseudocoelom (from between endoderm & mesoderm) – Growth requires ecdysis (molting) Mouth mesoderm Digestive tract Anus (from ectoderm) trochophore larva • Eucoelomate: cavity within (a) Body covering Figure 32.13 mesoderm Coelomate. annelid worm Coelom (from ectoderm)
Tissue layer lining coelom and suspending internal organs ecdysis (from mesoderm) Figure 32.8 Digestive tract Figure 32.12 (from endoderm)
Phylum Platyhelminthyes: Bilateral symmetry with cephalization “Flat Worms” • Embryonic development: – Triploblastic – Bilateral symmetry • Turbellarian w/ cephalization flatworm – No circulatory system – Gastrovascular cavity – Acoelomate • Special features: – Dorso-ventrally flattened
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Planarian anatomy – cross section Outer Body Covering • The body of some platyhelminthes (e.g., turbellarians) is covered by a ciliated epidermis. • Epidermal cells contain rod-shaped structures called rhabdites that when released into the surrounding water, expand and form a protective mucous coat around the animal
Muscular System • Below the epidermis are layers of circular and longitudinal muscle fibers; used in locomotion. • Pharynx develops as in-pocket of body wall; has similar musculature. •Esp. in larger spp., transverse parenchyma muscles extend through the loose connective tissue (parenchyma) from the dorsal to ventral surface. Flatten body and “flap” lateral “wings”.
Reproduction & Regeneration Phylum Platyhelminthyes • ~10,000 named spp.; >half parasitic
– Turbellarians: • aquatic free living/predatory – Trematodes (flukes) & Cestodes (tapeworms): • endoparasites
Phylum Nematoda (Nemata): Phylum Nematoda “Thread-like”: Round Worms • Embryonic development: – Triploblastic – Bilateral symmetry w/ cephalization – No circulatory system – Protostome – Pseudocoelomate – Ecdysozoa • Special features: – Most ubiquitous animal on earth!
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Phylum Annelida: Segmented Worms • Embryonic development: – Triploblastic – Bilateral symmetry w/ cephalization – Closed circulatory system – Protostome – Eucoelomate – Lophotrochozoa • Special features: – Segmentation – Hydrostatic skeleton
Annelida Eucoelomate Annelids • Body segments (metameres) Body wall (outer to inner layers): Gut wall (outer to inner layers): • Head I. Ectoderm: simple columnar epithelium I. Mesoderm: • Prostomium [“before mouth”] secretes a collagen cuticle 1. peritoneum: connective & epithelial II. Mesoderm: tissue — continuous with mesenteries anus • Peristomium [“around mouth”] 1. thin connective tissue layer and inner layer of body wall • Metameres (segments) 2. circular muscle 2. longitudinal muscle • Pygidium 3. longitudinal muscle 3. circular muscle • Growth zone 4. peritoneum: connective & epithelial 4. thin connective tissue layer tissue — continuous with mesenteries II. Endoderm: simple columnar or cuboidal mouth and outer layer of gut wall epithelium mouth anus
Coelom Body covering (from ectoderm)
Digestive tract Tissue layer (from endoderm) lining coelom and suspending internal organs (from mesoderm)
Annelida • 2 Classes Worm locomotion – Polychaeta – bristle worms ~12,000 spp. – Clitellata – earthworms & leeches ~ 5,000 spp.
- flatworms & larval annelids
Requires coordination of longitudinal + circular muscles - annelids
Only longitudinal muscles - roundworms & large flatworms
Tomopteris
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Platyhelminth locomotion head Outer Body Covering • The body of some platyhelminthes (e.g., turbellarians) is covered by a ciliated epidermis • Epidermal cells contain rod-shaped structures called rhabdites that when released into the surrounding water, expand and form a protective mucous coat around the animal Muscular System • Below the epidermis are layers of circular and longitudinal muscle fibers; used in locomotion
• Ciliary gliding: http://vimeo.com/11416114 • Sinusoidal undulations: http://www.youtube.com/watch?feature=fvwp&NR=1&v=7UkZHDIujUc
Earthworm locomotion Polychaete locomotion
• Video clips • http://www.youtube.com/watch?v=J8TfQUM8uu4&feature=fvwrel • http://www.youtube.com/watch?v=b5f4bitNJoU&feature=related
• Animations: • http://www.biology.ualberta.ca/courses.hp/zool250/animations/ Polychaete.swf
Polychaeta locomotion: shows the alternate contraction of the longitudinal muscles to form the wedge shape that results in the zig zag walking.
Earthworm locomotion Aquatic oligochaete locomotion
Segmentation è variation of sinusoidal: Helical swimming in ç direction of è Lumbriculus: wave & direction A unique form of animal backthrust of locomotion swimming
• Animations: http://www.biology.ualberta.ca/courses.hp/zool250/animations/Earthworm.swf • http://www.youtube.com/watch?v=oH8NMYi7qqw elapsed time (f1èf7) = 0.2 sec
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