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26.1 Introduction to Animals. Essential Question What makes an animal an “animal”?. What is an animal?. Members of Kingdom Animalia Multicellular Eukaryotic Heterotrophs. Bodies of most animals contain tissues . Tissues are groups of cells that perform a similar function
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26.1Introduction to Animals Essential Question What makes an animal an “animal”?
What is an animal? • Members of Kingdom Animalia • Multicellular • Eukaryotic • Heterotrophs
Bodies of most animals contain tissues • Tissues are groups of cells that perform a similar function • Epithelial tissue (like skin) cover body surfaces • Muscular tissue enable animals to contract and move body parts • Connective tissue (like bone and blood) support an animal’s body and connect its parts • Nervous tissue is composed of nerve cells which carry information throughout the body
95% of animals are invertebrates • Invertebrates are animals without backbones or vertebral column. • Sponges • Jellyfishes and corals • Sea stars and sea urchins • Worms • Insects
5% are vertebrates • Have a backbone • Fish • Amphibians • Reptiles • Birds • Mammals
What do animals do to survive? • Feeding • Respiration • Circulation • Excretion • Response to environment • Movement • Reproduction
Homeostasis • Maintaining a stable internal environment, with relatively constant properties such as temperature and pH. • For example – a dog pants when it gets too hot. This releases heat and reduces the body temperature.
Feeding • Must ingest food and then digest it • Herbivores eat plants • Carnivores eat other animals • Omnivores eat both plants and animals • Detritvores feed on decaying plants and animals • Filter feeders strain tiny floating organisms from the water • Form symbiotic relationships which can be symbiotic (helpful) or parasitic (harmful)
Respiration • All animals respire or take in oxygen and release carbon dioxide • Some animals rely on diffusion and absorb oxygen through their skin • Most animals have evolved complex tissues and organ systems like lungs
Circulation and Excretion • Many small aquatic animals rely on diffusion to transport oxygen, nutrients, and waste products to their cells. • Larger animals must have some kind of circulatory system to move materials throughout their bodies. • Ammonia is a primary waste product that must be eliminated through excretion.
Response and Movement • Nerve cells allow animals to respond to their environment • Receptor cells respond to stimuli such as light and sound • Some animals such as sponges stay attached to one spot (sessile) • Most animals are motile, which means that they can move by muscle contraction
Reproduction • Most animals reproduce sexually. • Sexual reproduction helps to create and maintain genetic diversity in populations. • Many invertebrates can reproduce asexually. • Asexual reproduction produces offspring genetically identical to the parent. • This allows an animal to increase offspring rapidly.
Trends in Animal Evolution • Complex animals have: • High levels of cell specialization • Internal body organization • Bilateral body symmetry • Front end or head with sense organs • Body cavity • Embryos develop in layers
Early Development • Animals that reproduce sexually begin life as a zygote or fertilized egg • Study of how an egg develops is called embryology • Zygote undergoes a series of divisions to form a blastula (hollow ball of cells) • The blastula folds on itself to form a blastopore (single opening) • The blastopore leads into a central tube that becomes the digestive tract.
Germ layers formed in one of two ways • Protostome - mouth is formed from the blastopore and includes most invertebrates. • Deuterostome – anus is formed from the blastopore and include echinoderms and all vertebrates.
Layers of Development • Embryos form germ layers: • Endoderm – innermost germ layer develop into digestive and respiratory system • Mesoderm – middle layer give rise to circulatory, reproductive, and excretory organ systems • Ectoderm – outermost layer gives rise to sense organs, nerves, and outer layer of skin
Body Symmetry • With exception of sponges, every animal exhibits some type of body symmetry • Radial symmetry – body divided into equal halves with many imaginary planes • Bilateral symmetry – single imaginary plane divides body into equal left and right sides.
Anatomy Vocabulary • Anterior – front end • Posterior – back end • Dorsal – upper side • Ventral – lower side
Cephalization • Cephalization - animals with bilateral symmetry exhibit a concentration of sense organs and nerve cells at the front end • Anterior end usually called a head. • Allows animals to respond to environment more quickly and in more complex ways • Usually move with anterior end forward so this end comes in contact with environment first • The more complex the animal the more pronounced their cephalization.
Body Cavity Formation • Most animals have a body cavity. This is a fluid-filled space that lies between the digestive tract and the body wall. • Important because they provide a space in which internal organs can be suspended. • Allow for specialized regions to develop and provide room for internal organs to grow and expand.
Body Cavities • Acoelomate– no true body cavity; mesoderm cells do not provide a specialized function. • Pseudocoelomate – false body cavity; body cavity isn’t completely lined with mesoderm. No muscular or connective tissues associated with the gut. • Eucoelomate– true body cavity; body cavity is completely surrounded by mesoderm. Organ systems are most advanced in this pattern.
Nine Animal Phyla to be Studied 1. Porifera – sponges 2. Cnidaria –jellyfish, coral, hydra 3. Platyhelminthes – flatworms 4. Nematoda – roundworms 5. Annelida – segmented worms (earthworms) 6. Mollusca – octopus, squid, snail 7. Echinodermata – sea stars, sea urchins, and sand dollars 8. Arthropoda – crayfish, pill bugs, insects, millipedes, and centipedes 9. Chordata – vertebrates (amphibians, reptiles, birds, fish, mammals)
26.1 Vocabulary • Blastula • Bilateral symmetry • Cephalization • Deuterostome • Ectoderm • Endoderm • Invertebrate • Mesoderm • Protostome • Radial symmetry • Vertebrate
Lesson Essential Questions • What characteristics do all animals share? • What are the seven essential functions that all animals carry out? • What is the difference between a invertebrate and a vertebrate? • What are important trends in animal evolution? • What is the difference between a protostome and a deuterostome? • In what ways are complex animals different from simple animals? • What are the three layers that develop in early animal embryos? • How do radial symmetry and bilateral symmetry differ?
