Introduction to Animals Unit 12 Intro to Dissection

Which one of these is an animal?

What makes an animal? Basic Characteristics

Intro to Animals Basic Characteristics: Heterotrophic Eukaryotic Multi-cellular Lack cell walls

Survival of Animals Maintain homeostasis Have a way of movement and support Gather and respond to information Obtain and distribute oxygen and nutrients Collect and eliminate CO2 and other wastes Reproduce

Animal Bodies Animals are classified based upon their body plans and patterns of embryological development

Features of a body plan Major features Body plan: Unique organization of particular body structures and how they perform life’s essential functions Major features Levels of organization Body symmetry Germ layers Body cavity Embryological development Segmentation Cephalization

In your notebooks Make a table that will help explain evolutionary relationships among animal phylum Major phylum vs. the major body plans features Sponges Cnidarians Flatworms Roundworms Annelids Mollusks Arthropods Echinoderms Chordates

Level of Organization Specialized Cells Tissues Organs Organ systems Sponges are the ONLY animal that contain one level of organization specialized cells Cnidarians have only have two

Body Symmetry Asymmetry (sponges, corals) No pattern Radial symmetry (starfish, cnidarians) Have multiple planes that can go through the center of the body Bilateral symmetry (flatworms, arthropods, chordates) Have only a single plane that divides the body equally into left & right sides

You try.....

Germ Layers Cells develop into 3 germ layers Ectoderm (outer) forms skin, nerves, sense organs Endoderm (inner) forms liver and lungs Linings of the digestive and respiratory systems Mesoderm (middle) forms muscles & circulatory, reproductive, and excretory systems NOT present in sponges Cnidarians only 2

Body Cavity Body cavity Acoelomate Pseduocoelomate True Coelomate a fluid-filled space between the digestive tract and body wall Acoelomate Pseduocoelomate True Coelomate

Coelomates Internal body cavity fully lined with mesoderm Body organs suspended in this cavity Complex animals

Acoelomates Sponges, Cnidarians and flatworms Lack a body cavity Solid body filled with cells

Pseudocoelomates Roundworms have a functional body cavity NOT fully lined with mesoderm Notice around the digestive tract wall

Embryological Development All life begins as a zygote and develops into a blastula (hollow ball of cells) Pinches in (like a finger in a balloon) and opening called blastopore Protostome Blastopore becomes the mouth Deuterostome Blastopore becomes the anus Echinoderms and Chordates

Segmentation Occurs whenever animal bodies are divided into repeating units or segments Found in more complex animals Earthworms show external segmentation Humans show internal segmentation (backbone)

Cephalization The concentration of sense organs and nerve cells at their anterior ends Known as the “head” Found in bilateral symmetrical animals Not present in sponges, Cnidarians, and Echinoderms

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Differences between animals Invertebrates- animals that do not have a backbone About 95% of animals Contain 33 different phylum Vertebrates- animals that contain a backbone About 5% of animals Contain phylum Chordates

4 main characteristics Notochord Pharyngeal Pouches Long supporting rod that runs through the body, most only have when they are embryos Pharyngeal Pouches Paired structures in the throat May develop into gills Pharynx in humans A tail that extends beyond anus Nerve cord

Animal Systems How do the structures of animals allow them to obtain essential materials and eliminate wastes? Systems: Feeding and digestion Respiration Circulation Excretion

Feeding and Digestion Obtaining food: Herbivore = eats plants Carnivore = eats animals Omnivore = eats plants and animals Detritivore = feed on decaying organic material Filter Feeders = aquatic animals that strain food from water Parasite = lives in or on another organism (symbiotic relationship)

Feeding and Digestion Processing Food: Intracellular Digestion Sponges and Cnidarians Passes nutrients through cells by diffusion Extracellular Digestion Process where food is broken down in digestive system Humans, etc.

Feeding and Digestion

Respiration Take in oxygen and let out CO2 Terrestrial Animals Aquatic Animals All use lungs Some have “special” features: Book Lungs (spiders) Tracheal tubes (insects) Skin (earthworm) Air sacs (birds) Gills Feathery structures that actively pump water over them

Respiration

Circulation Most animals move blood through their bodies by using one or more heart or hair-like structures Two major circulatory systems: Open (Arthropods and most mollusks) Blood is only partially contained in blood vessels Closed Completely contained in blood vessels

Circulation

Excretion elimination of metabolic wastes, such as ammonia Terrestrial Animals Aquatic Animals Invertebrates Annelids and mollusk produce urine in nephridia that leaves through pores Insects have malpighian tubes that absorb uric acid and combine it with digestive wastes Vertebrates Kidneys White paste in birds and reptiles All ammonia to diffuse out of their bodies into water In some cases, diffusion across the gill membrane

Response: Invertebrates Nervous System Nerve nets (cnidarians) Nerve cords (echinoderms) Ganglia (mollusks, arthropod, flatworm) Sensory organs Compound eyes Simple eye- detect movement Eyespot – detect light

Movement & Support Skeletons Hydrostatic (cnidarians and annelids) Fluids held inside, changes body shape Exoskeleton (arthropods and mollusks) Hard body covering made of chitin or shell made of calcium carbonate Molting Endoskeleton (echinoderms and chordates)

Reproduction Asexual vs. sexual (more to come later) Internal vs. External Fertilization (again more to come later)