Lesson Overview

1. Lesson Overview 25.1 What is an Animal?

2. Characteristics of Animals • Animals, which are members of the kingdom Animalia, are multicellular, heterotrophic, eukaryotic organisms whose cells lack cell walls.

3. Types of Animals Invertebrates : animals that lack a backbone, or vertebral column • 95 percent of animal species • include sea stars, worms, jellyfishes, and insects, like butterflies. Chordates (both invertebrate and vertebrate= 5% of animals species) : exhibit four characteristics during at least one stage of life: • a dorsal, hollow nerve cord • a notochord • a tail that extends beyond the anus • pharyngeal pouches

4. Chordates • Notochord: is a supporting rod that runs through the body just below the nerve cord. • Tail: extends beyond the anus at one point in their lives. • Pharyngeal pouches: structures in the throat region. • Most develop a backbone/vertebral column, (hence vertebrates), and include fishes, amphibians, reptiles, birds, and mammals.

5. What Animals Do to Survive • What essential functions must animals perform to survive? • They maintain homeostasis through negative inhibition (feedback) by: • gathering and responding to information • obtaining and distributing oxygen and nutrients • collecting and eliminating carbon dioxide and other wastes • Reproduce • feedback inhibition: a system in which the product or result of a process limits the process itself, (If you get too hot, you sweat, which helps you lose heat).

6. Gathering and Responding to Information • The nervous system gathers information using cells called receptors that respond to sound, light, chemicals, and other stimuli. • Other nerve cells collect and process that information and determine how to respond.

7. Gathering and Responding to Information • Nervous Systems: Neurons (specialized nerve cells): • Detect stimuli (sensory neurons) • Process information (interneurons-found in brain) • Respond (motor neurons-attached to muscle) • Invertebrates • Vertebrates

8. Gathering and Responding to Information • Invertebrate Nervous Systems: • Can be simple collections of nerve cells or • complex organizations which include interneurons • Sensory organs: more simple than vertebrates, • but can detect light, sound, vibrations, movement, chemicals, and body orientation • Vertebrate Nervous Systems: • Highly developed nervous systems with cephalization (heads) including interneurons within the head and sensory/motor neurons elsewhere in the body • Sensory organs: highly evolved sense organs

9. Gathering and Responding to Information • Movement and Support • The nervous system detects stimulus, processes information, and creates an action or movement by stimulating muscle tissue to relax or contract. • Muscles work with skeletons, tendons, and ligaments to make up the musculoskeletal system.

10. Gathering and Responding to Information Invertebrate Skeletons can be: • Hydrostatic: flexible and function through the use of fluid pressure, (earthworms) • Exoskeletons: external skeleton/support, (insects and lobsters-outer shells) Vertebrate Skeletons are: • Endoskeleton: internal skeleton./support, (humans-bones)

11. Obtaining Oxygen • Respiration • Gas Exchange: gas diffuses across a moist membrane. Carbon dioxide and oxygen can be exchanged on these membranes. • Aquatic animals • Can diffuse gas through their outer body covering • Most aquatic invertebrates and chordates use gills to exchange gas • Terrestrial Animals • Invertebrates: can diffuse gas through their skin or mantle cavity • Vertebrates: use lungs to exchange gas

12. Obtaining Nutrients • Feeding and Digestion • Most animals have a digestive system that acquires food and breaks it down into forms cells can use. • Animals transport oxygen and nutrients to cells throughout their bodies by using a circulatory system.

13. Obtaining Nutrients • Types of Feeding • Filter feeders: catch algae and small animals using gills-like structures as nets to filter food from water. • Detrivores: feed on decaying organisms. • Carnivores: eat other animals. • Herbivores: eat plants or parts of plants • Symbionts (parasitic/mutualistic): rely on another species to obtain nutrients.

14. Obtaining Nutrients • Digestion • Intracellular digestion: digestion happens inside specialized cells that pass nutrients to other cells by diffusion, (sponges and other simple animals). • Extracellular digestion: food is broken down outside cells in a digestive system and then absorbed, (more complex animals). • Gastrovascular cavities: a single opening in which food is digested and expelled. Specialized tissues carry out digestion and circulation, (cnidarians). • Digestive tracts: a tube that has two openings. Food moves in one direction entering the mouth and waste leaves through the anus, (many invertebrates and all vertebrates).

15. Circulating Nutrients • Circulatory systems • Include a heart-pumps blood • Open circulatory system: • Arthropods and mollusks • Blood is only partially contained within a system of blood vessels as it travels around the body • Closed circulatory system • Larger and more active invertebrates, mollusks, an all vertebrates • Blood circulates entirely within blood vessels in one direction

16. Collecting and Eliminating CO2 and Other Wastes • Waste Products: carbon dioxide, ammonia, and other waste products • toxic in high concentrations • eliminated from the body through the respiratory (CO2) or excretory system (ammonia and metabolic waste). • Aquatic Animals • ammonia can diffuse out of their bodies into the surrounding environment • Can be simple diffusion across the skin (some fish and amphibians), body surfaces, or gill membranes (many invertebrates and vertebrates)

17. Collecting and Eliminating CO2 and Other Wastes • Terrestrial Animals • Invertebrates: produce urine in nephridia (mollusks, annelids) or uric acid in malpighian ubules (insects and arachnids) • Vertebrates: excrete urea in urine (mammals, amphibians) or uric acid (birds and reptiles)

18. Reproduction • Asexual • invertebrates and a few vertebrates • One parent • offspring are genetically identical to the parent and there is less genetic diversity • Can produce many offspring in favorable, unchanging environments • Sexual • Most animals (vertebrates) • 2 Parents (Sperm/egg), provides genetic diversity • Produces less offspring, gives diversity to survive changing environments • Hermaphrodite • Individuals are born as one sex and change to the other sex over their life time • Can be both sexes at the same time

19. Reproduction • Internal Fertilization: eggs are fertilized inside the body. • Invertebrates: sponges, arachnids, arthropods • Vertebrates: some fish and amphibians, reptiles, birds, mammals • External Fertilization: eggs are fertilized outside the body. • Invertebrates: Corals, worms, mollusks • Vertebrates: some fish and amphibians

20. Lesson Overview 25.2 Animal Body Plans and Evolution

21. Features of Body Plans • Features of animal body plans include : • levels of organization • Body symmetry • differentiation of germ layers • formation of body cavities • patterns of embryological development • segmentation • cephalization • limb formation

22. Levels of Organization • celltissueorganorgan system organism

23. Body Symmetry • Types of Symmetry • radial symmetry: body parts extend from a central point, sea anemone • Bilateral Symmetry: a single imaginary plane divides the body into left and right sides that are mirror images of one another.

24. Differentiation of Germ Layers During embryological development, the cells of most animal embryos differentiate into three layers called germ layers. • Endoderm (inner layer): develop into the linings of the digestive tract and much of the respiratory system. • Mesoderm (middle layer): develop into muscles and much of the circulatory, reproductive, and excretory organ systems. • Ectoderm (outer layer): develop into sense organs, nerves, and the outer layer of the skin.

25. Formation of a Body Cavity • Most animals have some kind of body cavity—a fluid-filled space between the digestive tract and body wall that provides space for organs and room to grow. • Coelem: a body cavity that develops in the mesoderm and is completely lined with tissue derived from mesoderm, (complex animals). • Acoelemate: lack a body cavity altogether, (invertebrates). • pseudocoelom, which is only partially lined with mesoderm, (invertebrates)

26. Patterns of Embryological Development Sexual Reproduction • Egg is fertilized and is called a zygote. • The zygote develops into a hollow ball of cells called the blastula. • The blastula folds in on itself, forming a tube that runs from one end to the other that becomes the digestive tract.

27. Patterns of Embryological Development • Protostomes (most invertebrates): the blastopore becomes the mouth. • Deuterostomes (chordates and echinoderms), the blastopore becomes the anus.

28. Other Body Plans of Animals • Segmentation: repeating parts on animals with bilateral symmetry. • Worms, insects, and vertebrates • Cephalization: the concentration of sense organs and nerve cells at their anterior end. • Arthropods and vertebrates • Limb Formation: Segmented, bilaterally symmetrical animals typically have external appendages on both sides of the body. • Can be bristles (worms), jointed legs (spiders), wings (dragonflies), and limbs such as legs, flippers, and wings.

29. Body Plans • The body plans of modern invertebrates and chordates suggest evolution from a common ancestor.

30. The Cladogram of Animals • Animal phyla are typically defined according to adult body plans and • patterns of embryological development. • The evolutionary history presented in a cladogram represents a set of evolutionary hypotheses based on characteristics of living species, evidence from the fossil record, and comparative genomic studies.

31. Differences Between Phyla • The complicated body systems of vertebrates aren’t necessarily better than the “simpler” systems of invertebrates. • Within each phylum, different groups represent different variations on the basic body plan theme that have evolved over time.

32. Evolutionary Experiments • In a sense, you can think of each phylum’s body plan as an evolutionary “experiment,” in which a particular set of body structures performs essential functions. • If the changes successful, the members of the phyla survive and reproduce, if they are unsuccessful, members die without leaving offspringEXTINCTION!