Transcript Porifera: The Sponges - holyoke

Porifera: Very Simple Animals...(?)
Water in, water out
Sponges bring water in
through their pores and
move it out through the
large top opening. This
current provides:
-Food
-Respiration
-Excretion
-Circulation
-Reproduction
-No nervous system
-Many produce toxins
-Create many symbiotic relationships
(mutualism and commensalism)
Sexual Reproduction
-Sponges form both eggs and sperm
-The sperm move on current to other sponges
Asexual Reproduction
-A “bud” comes off the sponge and grows
-Produce “gemmules” in times of stress
-Jellies
-Hydra
-Anemones
-Corals
Cnidarians:
-Soft-bodied carnivores
-Have tentacles with specialized cells called
nematocysts that shoot poisonous darts into
prey (p. 669)
-Radial symmetry with a central mouth
surrounded by tentacles
-Have two stages in their life-cycle: a polyp and
a medusa. (p.670)
-Cnidarians paralyze prey with poison, then pull it
to their mouths and into the gastrovascular cavity
where it is digested. http://www.youtube.com/watch?v=o1A5acWEERA&feature=related
-They have a nerve net of specialized cells that allow
them to detect touch, light and gravity. (see next
slide)
-Use a hydrostatic skeleton to contract muscles for
movement. http://www.youtube.com/watch?v=760lUxyle6I
**Jellyfish use jet propulsion….muscle contractions cause the bell-shaped body to
close like a folding umbrella. This action pushes water out of the bell, moving the
medusa forward!
Hydra’s Nerve Net
-Sexual reproduction occurs through external fertilization
where the zygote is a free-swimming larva
-The larva attaches to a surface and forms a polyp.
-The polyp can reproduce asexually by budding young medusae.
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The Jellyfish: Class Scyphozoa..or “true” jellyfish
-Live lives primarily as medusas
-Range from tiny to almost 4 meters across with 30m long
tentacles
-reproduce sexually
-Some species are extremely venomous- The box jellyfish
(Class Cubozoa) Chironex fleckeri aka: Boxfish, Sea Wasp, Fire
Medusa, Or Just Stinger) is the most venomous animal in the
world and has killed over 5 500 people since the 1950s.
http://www.youtube.com/watch?v=pYUZxS1bZR4
Hydra and their Relatives
-Hydras belong to the class Hydrozoa
-Most hydrozoans are colonies of polyps performing
specialized functions (Portuguese Man O’ War)
-Hydra are freshwater hydrozoans that don’t have a medusa
stage. They only live as polyps.
Anemones and Corals
-This is the class Anthozoa (“flower animal”)
-Corals and anemones only have the polyp stage
-Anemones are solitary polyps
-Corals form colonies of polyps that look like tiny anemones.
-Colonies grow over thousands of years producing calcium
carbonate structures that build huge reefs that are threatened.
-Corals form mutualistic relationships with algae.
http://www.youtube.com/watch?v=60jof35WuAo