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Introduction to animals. Introduction to Animals – Ch. 32. The Nature of Animals. Section 32.1. Classification :. 95-98% of animals are invertebrates Without a backbone 2-5% of animals are vertebrates With a backbone. Animal Traits. Characteristics:. All animals are: Multicellular
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Introduction to animals Introduction to Animals – Ch. 32
The Nature of Animals Section 32.1
Classification: • 95-98% of animals are invertebrates • Without a backbone • 2-5% of animals are vertebrates • With a backbone
Characteristics: All animals are: • Multicellular • Eukaryotic • Ingestive heterotrophs • Lacking in cell walls • Sexually reproductive • Able to move
1. Multicellular Organization • Cell specialization: the evolutionary adaptation of a cell for a particular function • Tissue: group of similar cells that perform a common function • Cell junctions: connections between cells that hold them together as a unit
Molecule or compound Atom Organelle Levels of Organization CELL Life begins Tissue Organ Organ system Organism
3. Ingestive Heterotrophy • Getting complex organic compounds (carbon) from sources other than the sun • Ingestion: taking in food usually in the form of an other organism • Digestion: the body’s process of extracting organic molecules from food
5. Sexual Reproduction & Development • Hermaphrodites: producing both eggs and sperm • Examples: worms & sponges • Most do NOT fertilize own eggs • Why not? • Zygote: diploid cell that results from the fusion of two haploid gametes • Undergoes differentiation (cells becoming specialized to perform a specific function)
Female Beetles Mating Young Courtship Male Mating and Mating Behaviors
Leeches Exchange Sperm During Mating leech Mating
Parthenogenesis: • Females of some animals produce eggs, but the eggs develop without being fertilized! • New offspring will be all female • Example animals: some fishes, several kinds of insects, and a few species of frogs and lizards
6. Movement • Sessile: attached & non-moving • sponges • Sedentary: move very little • clam • Motile: animals that can move • humans • Ability to move depends upon interaction between nervous tissue and muscle tissues • Neurons:cells of nervous tissue
SESSILE SEDENTARY Chiton Sponge MOTILE Cheetah
Origin of Animals: • Animals came about in the water • Evolved from colonial protists: • Each organism had its own function (for the colony) much like each cell of the animal body has its own function (for the organism) Video
Body Structure: • Symmetryis the arrangement of body parts around a central plane or axis • Asymmetryoccurs when the body can’t be divided into similar sections • sponges
Radial symmetry • when body parts are arranged around a central point • like spokes on a wheel • echinoderms • Most animals are sessile (attached) or sedentary (move very little)
Bilateral symmetry • when animals can be divided into equal halves along a single plane • right and left sides that are mirror images of each other • are usually motile • Show cephalization • concentration of sensory organs on the head (anterior) end
Segmentation • When an animal body is composed of a series of repeating similar units • Example: earthworm (annelid) • Segments may look different & have different functions • Example: insects & crustaceans (arthropods)
Anatomical Terms: Dorsal: back surface of animal Ventral: underside of animal Anterior: front end of animal Posterior: rear end of animal Lateral: sides of animal Medial: along midline of animal Proximal: near to Distal: away from
