introduction to animalssection 2 ch 26:introduction to animals sec 1 and sec 2
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Introduction to Animals Section 2
CH 26: Introduction to Animals
Sec 1 and Sec 2
Introduction to Animals Section 2
General Features of Animals
• Animals are multicellular, heterotrophic organisms with cells that lack cell walls.
• Humans depend on other animals for food, companionship, and to pollinate crops.
• Most animals move to get food. But filter eaters, such as sponges and corals, catch particles of food that drift by in the water.
Introduction to Animals Section 2
Kinds of Animals
• Animals are often grouped as invertebrates or vertebrates.
• Vertebrates make up only a subgroup of one phylum—Chordata.
• Most animals are invertebrates.
Introduction to Animals Section 2
Kinds of Animals, continued
Vertebrates• Vertebrates have a cranium and an internal skeleton
composed of bone or cartilage.
• Vertebrates are chordates that have a backbone.
• The backbone supports and protects a dorsal nerve cord and provides a site for muscle attachment.
• Pg 625
Introduction to Animals Section 2
CH26 Sec 2: Animal Body Systems
Introduction to Animals Section 2
Key Ideas• Why is an animal's skeleton important?
• What are the functions of the digestive and excretory systems?
• What is the function of the nervous system?
• Why are the respiratory and circulatory systems important?
• What are two reproductive strategies of animals?
Introduction to Animals Section 2
Support
• An animal's skeleton provides support for the animal's body and location for muscle attachment.
• Many soft-bodied invertebrates, such as jellyfish, have a hydrostatic skeleton– which is a water-filled cavity that is under pressure.
• An exoskeleton is a rigid external skeleton that encases the body of an animal.
• An endoskeleton is an internal skeleton made of bone and cartilage.
Introduction to Animals Section 2
Digestive and Excretory Systems
• The digestive system is responsible for extracting energy and nutrients from an animal's food.
• The excretory system removes waste products from the animal's body.
Introduction to Animals Section 2
Digestive System• A gastrovascular cavity
is a digestive cavity with only one cavity.
• The hydra has a gastrovascular cavity.
Introduction to Animals Section 2
Digestive System, continued• In a digestive tract, food moves from one opening, the
mouth, to a second, the anus.
• Digestive tracts allow for specialization and more efficient digestion.
Introduction to Animals Section 2
Digestive and Excretory Systems, continuedExcretory System• The removal of wastes produced by cellular metabolism.
• Simple aquatic invertebrates and some fishes excrete ammonia through their skin or gills.
• Terrestrial animals need to minimize water loss.
Introduction to Animals Section 2
Nervous System
• Carries information about the environment through the body and coordinates responses and behaviors.– Nerve net– Ganglia– Brain
Introduction to Animals Section 2
Hydra Nervous System
Introduction to Animals Section 2
Flatworm Nervous System
Introduction to Animals Section 2
Grasshopper Nervous System
Introduction to Animals Section 2
Respiratory and Circulatory Systems
• The respiratory system is responsible for exchanging oxygen and carbon dioxide between the body and the environment. – Gills – Lungs
• The circulatory system transports gases, nutrients, and other substances within the body.
Introduction to Animals Section 2
Circulatory System• Open circulatory system
– a heart pumps fluid containing oxygen and nutrients through vessels into the body cavity.
– The fluid provides oxygen and nutrients as it washes across the tissues.
• Closed circulatory system– the blood is pumped through the body within vessels – is never in direct contact with the body's tissues.
Introduction to Animals Section 2
Open and Closed Circulatory Systems
Introduction to Animals Section 2
Reproduction• Asexual reproduction occurs when an individual produces
exact copies of itself and gametes are not exchanged.– Budding– Parthenogenesis– Fragmentation
• Sexual reproduction, a new individual is formed by the union of a male and female gametes.
• Some species can reproduce either asexually or sexually.