Animal Kingdom Ch 25 What is an Animal?

Important Animal Facts Animal Kingdom can be split up into main groups, vertebrates (with a backbone) and invertebrates (without a backbone). 95% of animals are invertebrates.

Characteristics of Animals Eukaryotic Multicellular heterotrophic. Various methods of obtaining food based on environment in which they live. Methods of locomotion (movement) that aid in reproduction, feeding, and escaping predators Sexual reproduction

Fixed size and shape at adulthood No cell walls Specialization-cells are grouped to form tissues organs, and organ systems to carry out different functions: –Sense and locate food, mates, and shelter –Conduct information, transport oxygen and nutrients etc. –Respiratory, circulatory, excretory, digestive, nervous, reproductive, muscular, skeletal.

Invertebrates-no backbone (95% of all animals) Vertebrates- (chordates) have a backbone

Patterns of Symmetry Body Symmetry – the body plan of an animal, how its parts are arranged Asymmetry-irregular shape, no pattern (sponge) Radial Symmetry-the body parts are arranged in a circle around a center point –can detect prey and predators from all direction –shaped like a wheel (starfish, hydra, jellyfish)

Bilateral Symmetry Bilateral Symmetry – can be divided lengthwise into identical right and left sides (humans, butterfly, lizard, cats, etc) –Advantages-can find food, mates, avoid predators due to good muscle control and the presence of sensory organs –anterior – toward the head –posterior – toward the tai –dorsal – back side –ventral – belly side –Cephalization – sensory organs located near the anterior area of body *The more complex the animals becomes, the more pronounced their cephalization.

Animal Development-cell division Zygote = fertilized egg, undergoes mitosis to form an embryo

The cells of most animal embryos differentiate into three layers called germ layers: –Endoderm = (innermost) develops into the lining of the digestive tract and respiratory tract –Mesoderm = (middle) muscle, circulatory, reproductive, and excretory systems –Ectoderm = (outermost) sense organs, nerves, outer layer of skin

Animal Protection and Support Exoskeleton- hard waxy outer covering that supports body tissues, provides protection, and prevents water loss. Endoskeleton-internal skeleton covered by layers of cells protects internal organs, supports muscles, and aids in movement; all vertebrates

Main group of Invertebrates are : Porifera (sponges) Cnidaria (jellyfish, hydras, sea anemones, Portuguese man-of-wars, and corals) Platyhelminthes (flatworms, including planaria, flukes, and tapeworms) Nematoda (roundworms, including rotifers and nematodes) Mollusca (mollusks, including bivalves, snails and slugs, and octopuses and squids) Annelida (segmented worms, including earthworms, leeches, and marine worms) Echinodermata (including sea stars, sea cucumbers, sand dollars, and sea urchins) Arthropods (including arachnids, crustaceans, millipedes, centipedes, and insects) Chordata (animals with nerve chords - this group includes the vertebrates)