unit 8 invertebrates ch. 26 sponges & cnidarians
TRANSCRIPT
Unit 8 Invertebrates
Ch. 26 Sponges & Cnidarians
Introduction to the Animal Kingdom
Animals, members of the kingdom Animalia, are multicellular, eukaryotic heterotrophs whose cells lack cell walls
What Is an Animal?
Invertebrates - animals that do not have a backbone, or vertebral column
Vertebrates - animals with a backbone
What Animals Do to Survive
Animals carry out the following essential functions: feeding, respiration, circulation, excretion, response, movement, & reproduction
What Animals Do to Survive
FeedingMost animals cannot absorb food, instead,
they ingest (or eat) it
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
What Animals Do to Survive
CirculationSmall animals rely on diffusion to transport
nutrientsLarge animals have a circulatory system to
move nutrients around
What Animals Do to Survive
Excretion Most animals have an excretory system that
eliminates wastes, maintaining homeostasis
What Animals Do to Survive
ResponseAnimals respond to events in their
environment using specialized cells called nerve cells
What Animals Do to Survive
MovementMost animals are motile, meaning they can
move around
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
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
Trends in Animal Evolution
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
Body Symmetry
Trends in Animal Evolution
Cephalization - the concentration of sense organs & nerve cells at the front end of the body
What Is a Sponge?
Sponges are classified as animals because they are multicellular, heterotrophic, have no cell walls, & contain a few specialized cells
Form & Function in Sponges
The movement of water through the sponge provides a simple mechanism for feeding, respiration, circulation, & excretion
Ecology of Sponges
Sponges often provide habitats for other organisms
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
Form & Function in Cnidarians
Cnidarians typically have a life-cycle that includes 2 different-looking stages: a polyp & a medusa
Form & Function in Cnidarians
ResponseMany cnidarians respond to touch by pulling
their tentacles inside their bodies
Form & Function in Cnidarians
MovementJellyfishes move by means of jet propulsionThe body contracts to force water out,
moving the jellyfish in the opposite direction
Groups of Cnidarians
Cnidarians include jellyfishes, hydras & their relatives, & sea anemones & corals
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
Groups of Cnidarians
Hydras live solely as polypsEx.) Portuguese man-of-war
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
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