unit 8 invertebrates ch. 26 sponges & cnidarians
TRANSCRIPT
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Unit 8 Invertebrates
Ch. 26 Sponges & Cnidarians
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Introduction to the Animal Kingdom
Animals, members of the kingdom Animalia, are multicellular, eukaryotic heterotrophs whose cells lack cell walls
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What Is an Animal?
Invertebrates - animals that do not have a backbone, or vertebral column
Vertebrates - animals with a backbone
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What Animals Do to Survive
Animals carry out the following essential functions: feeding, respiration, circulation, excretion, response, movement, & reproduction
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What Animals Do to Survive
FeedingMost animals cannot absorb food, instead,
they ingest (or eat) it
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What Animals Do to Survive
Respiration Whether they live in water or on land, all
animals respire, they take in oxygen & give off carbon dioxide
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What Animals Do to Survive
CirculationSmall animals rely on diffusion to transport
nutrientsLarge animals have a circulatory system to
move nutrients around
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What Animals Do to Survive
Excretion Most animals have an excretory system that
eliminates wastes, maintaining homeostasis
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What Animals Do to Survive
ResponseAnimals respond to events in their
environment using specialized cells called nerve cells
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What Animals Do to Survive
MovementMost animals are motile, meaning they can
move around
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What Animals Do to Survive
ReproductionMost animals reproduce sexually, which
helps create & maintain genetic diversity in populations
It improves the species ability to evolve when the environment changes
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Trends in Animal Evolution
Complex animals tend to have high levels of cell specialization & internal body organization, bilateral body symmetry, a front end or head with sense organs, & a body cavity
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Trends in Animal Evolution
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Trends in Animal Evolution
Body symmetryRadial symmetry - similar to a bicycle wheel,
any number of imaginary planes can be drawn through the center
Bilateral symmetry - a single imaginary plane can divide the body into 2 equal sides
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Body Symmetry
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Trends in Animal Evolution
Cephalization - the concentration of sense organs & nerve cells at the front end of the body
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What Is a Sponge?
Sponges are classified as animals because they are multicellular, heterotrophic, have no cell walls, & contain a few specialized cells
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Form & Function in Sponges
The movement of water through the sponge provides a simple mechanism for feeding, respiration, circulation, & excretion
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Ecology of Sponges
Sponges often provide habitats for other organisms
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What Is a Cnidarian?
Cnidarians are soft-bodied, carnivorous animals that have stinging tentacles arranged in circles around their mouths
They are the simplest animals to have body symmetry &
specialized tissues
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Form & Function in Cnidarians
Cnidarians typically have a life-cycle that includes 2 different-looking stages: a polyp & a medusa
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Form & Function in Cnidarians
ResponseMany cnidarians respond to touch by pulling
their tentacles inside their bodies
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Form & Function in Cnidarians
MovementJellyfishes move by means of jet propulsionThe body contracts to force water out,
moving the jellyfish in the opposite direction
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Groups of Cnidarians
Cnidarians include jellyfishes, hydras & their relatives, & sea anemones & corals
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Groups of Cnidarians
Like many marine organisms, jellyfishes use bioluminescence, or the production of light by an organism, to ward off predators
The entire body becomes bioluminescent when threatened
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Groups of Cnidarians
Hydras live solely as polypsEx.) Portuguese man-of-war
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Groups of Cnidarians
Sea anemones are polyps that live at all depths of the ocean
Coral reefs are home to many types of organisms & are as diverse as rain forests
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Ecology of Corals
In normal conditions, algae live within coral tissues, carrying out photosynthesis & giving the coral its green appearance
When stressed by pollutants or increasing temps., these algae can die, so only the clear cells of the coral remain