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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
Comparison of Invertebrates & Vertebrates Section 32.2
Invertebrate groups Video!
Invertebrates • Simplest animals • Contain the greatest number of different species • Most are aquatic • Do NOT have a backbone • Includes: • sponges, cnidarians, flatworms, roundworms, annelids, mollusks, arthropods, & echinoderms
Sponges – Phylum Porifera Osculum of Sponge
Sea Anemone – Phylum Cnidaria Tentacles of Sea Anemone
More Phylum Cnidaria Brain Coral Red jellyfish *
Flatworms – Phylum Platyhelminthes Marine Flatworm Planarian
Roundworms - Phylum NematodaSegmented Worms – Phylum Annelida Nematode Leech (segmented worm)
Phylum Mollusca (With and Without Shells) snail scallop octopus nudibranch nautilus
Phylum Arthropoda spider crayfish Horseshoe crab Dung beetle
Phylum Echinodermata Sea fan (crinoid) starfish Brittle star Sand dollar Sea cucumber
Symmetry • Most are radial or bilateral • Radial can receive stimuli and move in any direction (in water) • Some are highly cephalized Bilateral but NOT an invertebrate Bilateral Radial
Support of the Body • Various types of support: • Simple skeletons(sponges) • Fluid-filled body cavity (roundworms) • Exoskeleton (crayfish) • Rigid outer covering for protection of soft tissue
2 Types of Circulatory Systems: • Open circulatory system: circulatory fluid is pumped by the heart through vessels into a body cavity • Arthropods & most mollusks • Closed circulatory system: circulatory fluid is restricted to vessels in a closed loop • Squid (mollusk) Video
Digestive & Excretory Systems • Gut: a digestive tract running through the body • Liquid wastes are excreted as ammonia • highly toxic
Development • Indirect Development:an intermediate larval stage occurs • Flies • Direct development:young animal appears similar to adult • grasshoppers
Indirect Development
Vertebrate Groups Video!
Fishes – Classes Myxini, Cephalaspidomorphi, Chondrichthyes, Actinopterygii, and Sarcopterygii lancelet ray damselfish anglerfish
Class Amphibia salamander toad frog newt
Class Reptilia Turtle Snake Lizard Alligator