Multicellular Eukaryotes Notes From Slides

Multicellular eukaryotes Heterotrophs Consumers not producers (Autotrophs) Cellular specialization Specific functions e.g., phagocytosis, conductance, transport Diverse body plans Adaptations for feeding, reproduction, waste removal, etc. Movement (locomotion) Use contractile proteins- muscles System level or organization Nervous, muscle, circulatory, etc. Humans have 11 systems Reproduction Sexual reproduction Large, non-motile egg Small, flagellate sperm Diploids (2N) Embryonic development Zygote (post fertilization) Metamorphosis Change in body form avoids competition during development to adult Complete 4 different body forms during development Avoids competition Incomplete Direct development More subtle differences between young and adult Nymphs are immature stages Instar time between molting and until mature Observed in arthropods Marine Advantages Buoyancy Provides support good for invertebrates and large vertebrates Fluid balance More easily maintained than on land Isosmotic body fluids (-same osmotic concentration as H2O) Large food source (plankton) Disadvantages Continuous motion Hard to maintain position Salinity Affects solvent solubility (e.g., O2) Freshwater More difÏcult of water environments Disadvantages Outweigh advantages Fluid balance Body fluids hypertonic to water Food Generally less than in seas or oceans Adaptations for surviving variation in O2 content, temperature etc. Estuaries Fresh water and saltwater meets Problems Combination of both fresh and saltwater problems Significant salinity changes as move toward saltwater area Terrestrial Advantages – no longer have problems faced in water Disadvantages Desiccation Water loss across body surfaces Drying out of gametes Gravity Temperature extremes Clade Radiata Body symmetry Radial Body shape Circular or tube-shaped Structural arrangement Spokes around central axis Result Multiple planes through central axis produces two similar things Body Surfaces Only two surfaces and no other orientation apply as sseen in animals with bilateral symmetry Oral Mouth surface Aboral Clade Bilateria Body symmetry Bilateral Result Single plane (midsagittal produces similar right and left halves Sagittal plane Divides body into right and left parts Frontal plane Divides body into dorsal and ventral parts Transverse plane (cross section) Cuts at right angles to long axis Cephalization Majority of animals with bilateral symmetry Clade animalia Tissues Closely associated, similar cells working together to carry out specific functions Germ layer Formed early in development Gives rise to specific types of tissues Three primary germ layers Ectoderm – outher Endoderm- inside Mesoderm -in between Diploblastic Organism Have two germ layers Ectoderm Endoderm Diploblastic only Clade radiata (No mesoderm) Triploblastic Organisms Have three germ layers Triploblastic clades Bilateria (bilateral symmetry) Acoelomate No body cavity between two tissue layers Coelomate (Eucoelomate0 Description True body cavity Fully lined by mesoderm Location Between body outer wall and digestive tube Pseudocoelomate Description - Lined by meso derm on outer surface Lined by endoderm on inner surface Falso body cavity Significance of the Coelom Provied Space Room for internal organs Allows for movement and function Can serve as a hydrostatic skeleton Muscles push against a tube of liquid (later) Mammalian diaphragm Divides coelom into two cavities Embryonic Development in Bilateria Blastospore defined Opening in the blastocyst Fate of blastospore Protostomes o o First opening = mouth Second opening = anus Deuterostomes o o Cleavage First opening = anus Second opening = mouth Protostomes o o Spiral (when the cell divides its like going up a stair case) Determinate Deuterostomes o o Radial Indeterminate (identical twins) Coelom formation Protostomes o o Schizocoelous Mesoderm splits Deuterostomes o o Enterocoeles Out pocketing of mesoderm Clades within Bilateria and Prostomia Protsotomia [two clades] Lophotrochozoa o Ciliated ring around the mouth Trochophore o Ciliated larve Ecdysozoa o o Undergo ecydysis (molting) of exoskeleton Ex: nematodes Echinodermata Chordata