Chapter 26 INTRODUCTION TO ANIMALS

1. Chapter 26INTRODUCTION TO ANIMALS BIOLOGY II

2. Artemia (brime Shrimp) • http://www.youtube.com/watch?v=ZQXCa2TgcM4

3. Facts • The Great Salt Lake brine shrimp population can produce four or more generations per year. Brine shrimp are crustaceans. Their closest relatives include fairy shrimp, triops and water fleas. More distant relatives include crabs, lobsters and shrimp.Brine shrimp are used in the laboratory for testing the toxicity of chemicals.Brine shrimp cysts have been found in Great Salt Lake geologic core samples up to 600,000 years old, so we know they've been in the area for a long time.Brine shrimp cysts are packaged and sold as Sea-Monkeys.Brine shrimp cysts can remain viable for up to 25 years.Brine shrimp come in many colors. From white to pink to green, the different colors are probably an effect of diet and environmental conditions.

4. Taxonomy • Kingdom: Animalia • Phylum: Arthropoda • Subphylum: Crustacea • Class: Branchiopoda (like fairy shrimp, daphnia, tadpole shrimp) • Order: Anostraca • Genus and Species: Artemiafranciscana

5. Section 1- Characteristics of Animals • Purpose of this section: • Is to describe the features that all animals have in common • Learn about some of the major developments that occurred in animals as they evolved • How major groups of animals differ from each other

6. General features of animals • Mites = need microscope • Whales = huge • Animals are multicellular, heterotrophic organisms with cells that lack cell walls

7. multicellularity • All animals are multicellular (many cells) • Large differences in body sizes of animals, but most of the cells that make up these animals are similarly sized Humpback Whale Daphnia

8. Stop and Think • What do cells need to survive? • Oxygen, source of energy, waste removal, access to water and other organic and inorganic molecules, a temperature above freezing • How do the cells that make up skin get the things they need? • Depend on cells in body systems to provide what they need • Example circulatory system

9. Heterotrophy • Animals are heterotrophs • Cannot make their own food • Must seek our food sources in their environment • Food is eaten and then digested in a cavity inside the body • Some, like sponges and corals catch food that drifts by • Filter feeders

10. movement • Are unique because they can perform rapid, complex movements • Lack of cell wall, means greater mobility • Move by means of muscle cells that contract with considerable force • Cheetah • Chases the Gazelle • Reaches speeds of 60 mph • Fastest land animals

11. Kinds of animals • Kingdom animalia contains about 35 major divisions called phyla (singular, phylum) • Often classified by development or body characteristics • Informally grouped as invertebrates or vertebrates • However, vertebrates make up only small subgroup of one phylum (Chordata) • Majority of animals are invertebrates

12. invertebrates • Include any animal that does not have a backbone • Primitive(sponges) – advanced (ants, octopuses) • Land inverts tend to be small, no skeleton for support • Ocean inverts can be extremely large, giant squid (42 ft. in length) • Some form basis of entire ecosystem • Great Barrier Reef, 2,300 km long, made of coral

13. Vertebrates • Are chordates that have a backbone • Also have a cranium and an internal skeleton composed of bone or cartilage • Backbone supports dorsal nerve cord • Provides site for muscle attachment End 26.1

14. Journal Entry – Stop and Think • Write the date at the top of your clean journal page. A classmate tells you that sponges are plants because they attach themselves to the bottom of the ocean. Is your classmate correct? Explain your answer.

15. 26.2 Animal Body Systems • Body systems allow animals to function • Not all animals have every system • SUPPORT • Key to success = mobility • Mobility requires the body to have support • Skeleton provides framework that supports body

16. Types of Skeletons • Hyrodstatic • Water-filled cavity that is under pressure • Similar to balloon filled with water • Ex – jellyfish • Exoskeleton • Rigid external skeleton • Provides surface for muscles to pull against • Ex – insects, clams, crabs • Endoskeleton • Made of hard material, such as bone, inside an animal • Ex – humans and other vertebrates

17. Digestion • Single-celled organisms and sponges digest food within their body cells (no digestive system) • Food source cannot be larger than individual cells • All other animals digest food extracellularly (outside of body cells) within a digestive cavity • Enzymes are released into the cavity to breakdown the food • Allows animals to prey on organisms larger than their body cells

18. Digestion, cont. • Simple animals, such as hydra and flatworms, have a gastrovascular cavity • a digestive cavity with only one opening. • Other animals have a digestive tract (gut) with two openings, a mouth and an anus. • Allows for specialization • Sections of gut for food storage, breakdown of food, chemical digestion, etc.

19. Excretory system • The removal of wastes produce by cellular metabolism • Build up of waste products will hurt or kill an organism • Simple aquatic invertebrates • Excrete ammonia through their skin or gills • Also results in loss of water • Ok, because they are in water… • Terrestrial animals • Must minimize water loss • Convert ammonia to urea (component of urine)

20. Simple nervous systems • Nerve cells (neurons) are specialized for carrying messages in the form of electrical impulses (conduction) • Coordinate to help body respond to environment • All major animal phyla except sponges have nerve cells • Simplest arrangements can be found in hydras and jellyfish • Nerve cells are all similar looking and are linked in a web called a nerve net • Little coordination among nerve cells • Ganglia – clusters of neurons (found in bilaterally symmetrical animals) • Can be clustered, similar to a brain

21. Complex nervous systems • Have a true brain with sensory structures like eyes • Can interact with environment in complex ways • Vertebrates have most advanced nervous system

23. Respiration • Simple animals (jellyfish) • Oxygen gas and carbon dioxide gas are exchanged directly with the environment by diffusion • Uptake of oxygen and release of carbon dioxide (respiration) can take place only across a moist surface • Larger, complex animals • Simple diffusion cannot provide adequate gas exchange • Have specialized respiratory structures • Gills – very thin projections of tissue to aid aquatic animals in respiration • Not suitable in land animals because they must be kept moist • Lungs – evolved for terrestrial animals

24. Circulation • Simple animals • Body cells are exposed to either the external environment or gastrovascular cavity • No body cells are far away from sources of oxygen and nourishment • Complex animals • Have tissues that are several cell layers thick • Not close enough to surface of the cell layer to exchange materials directly with the environment • Oxygen and nutrients must be transported by a circulatory system

25. Types of circulatory systems • Open circulatory system • Heart pumps fluid containing oxygen and nutrients through a series of vessels out into the body cavity • Fluid washes across the body’s tissues, supplying them with oxygen • Fluid collects in open spaces and then flows back to the heart • Closed circulatory system • Heart pumps blood through a system of blood vessels • Form a network that permits blood flow from the heart to all of the body’s cells and back again • Blood does not come in contact with the body’s tissues • Oxygen and materials pass into and out of the blood by diffusion through the walls of blood vessels

27. Reproductive strategies • Not essential to survival for an individual organism • Reproduction is necessary for the survival of a species

28. Asexual reproduction • Does not involve the fusion of two gametes • Sponge – fragments it body • Each grows into a new sponge • Some sea anemones pull themselves apart to form two new adults • Animals that reproduce asexually are usually able to also reproduce sexually.

29. Sexual reproduction • Organism is formed by the union of a male and female gamete • Gametes are produced in sex organs • Testes produce male gametes (sperm) • Ovaries produce female gametes (egg) • Hermaphrodites – have both testes and ovaries • Functions as both male and female • Sperm and egg are usually produced at different times, so self-fertilization does not occur • END 26.2

30. 26.3 evolutionary trends in animals • Animals appeared about 650 mya (in oceans)

31. tissues • Except sponges, cells of all animals are organized into units called tissues • Groups of cells that work together to perform a specific function

32. Body symmetry • All animals have a body plan • Describes the shape, symmetry, and internal organization • ASSYEMETRICAL • Simplest body plan (sponges) • IRREGULAR in shape, shape depends on where they are growing

33. Radial symmetry • Have body parts arranged around a central axis, like spokes on a bicycle wheel • A plane passing through the central axis divides the organism roughly into equal halves • Today’s radially symmetrical animals are aquatic • Most drift slowly or drift in ocean currents

34. Bilateral symmetry • Distinct left and right halves • Plane passes through body and divides the animal into mirror image halves • Major evolutionary change in animals because it allowed animals to become specialized • Cephalization – evolved an anterior concentration of sensory structures • Can more easily sense food and danger with sense organs in the front.

36. Early embryonic development • Cleavage – series of cell divisions • Blastula – stage before gastrulation – hollow ball of cells • Gastrulation – from blastula to gastrula – forms embryonic germ layers

37. Blastula formation • In all animals except sponges, the zygote (fertilized egg cell) undergoes cell division that form a hollow ball of cells called a blastula • Cells develop into three distinct layers of cells • Ectoderm • Endoderm • Mesoderm • Called primary tissue layers, which give rise to all of the tissues and organs in the body

38. TISSUE Layers • Ectoderm • Outer layer of skin • Nervous system • Sense organs, such as eyes • Endoderm • Lining of digestive tract • Respiratory system • Urinary bladder • Digestive organs • Liver • Many glands • Mesoderm • Most of the skeleton • Muscles • Circulatory system • Reproductive organs • Excretory organs

39. Twins form in one of two ways • Dizygotic (fraternal) twins results when ovulation produces two eggs that are fertilized by different sperm • Can be as genetically dissimilar as any two siblings • Monozygotic (identical) twins result when an embryo splits in two early in cleavage, giving rise to two genetically identical embryos. • ***Incidence of twin pregnancies is about 11 per 1,000 pregnancies ( 1 in 90) • ***Dizygotic twins is 4-50 per 1,000 pregnancies, and monozygotic is 1-5 per 1,000

40. Patterns of development • Gastrula continues to change as it develops • Inward folding pocket becomes deeper • Eventually pocket breaks through the opposite side • Changes pocket to passageway • Lined with endoderm • Is gut of developing embryo • Page 635 (pictures)

41. protostomes • Mouth develops from end of embryo near blastopore • Anus develops at the opposite end • Ex – flatworms, earthworms, snails and clams, spiders and insects, and the relatives of these animals

42. deuterostomes • Mouth develops from end opposite of blastopore • Anus develops at or near blastopore • Ex – sea stars and relatives and vertebrates and relatives • First animals to have internal skeleton

43. Internal body cavity • Bilaterally symmetrical animals have one of three basic kinds of internal body plans • May include a coelom – fluid filled space found between the body wall and the digestive tract (gut) • This space is lined with cells that come from mesoderm

44. aCOELomates • Have no body cavity • Space between body wall and gut is completely filled with tissue Trematoda

45. pseudocoelomates • Have a body cavity located between the mesoderm and endoderm • Body cavity is called a pseudocoelom (false coelom) Rotifera

46. coelomates • Have a true coelom • Provides an internal space where mesoderm and endoderm can be in contact with each other during embryonic development • Aided in evolution of complex organs

48. Body Segmentation • Can allow great mobility and flexibility • Earthworm can tie body in knots • Lengthens and shortens body to move • Offers evolutionary flexibility • Small change in existing segment can produce new type of segment with different function • Feeding or moving • Reproduction, etc. • End 26.3

49. 26.4 Chordate evolution • First chordates appeared 500 mya • At some point in development, all chordates have: • Dorsal nerve cord • Notochord • Pharyngeal pouches • Postanal tail

50. Dorsal nerve cord • Single, hollow dorsal nerve cord with nerves attached to it that travel to different parts of the body • In vertebrates, develops into spinal cord