What would you do if you were

stung by a jellyfish?

Cnidarians-Another very diverse group including:

Jellyfish

Anemones

Hydroids

Coral

BoxJellyfish

**Simplest organisms with a tissue level of organization!

Cnidarians1) Radial Symmetry – Can be sliced evenly like slices of a pizza

Cnidarians2) Main body composed of 2 layers – epidermis/gastrodermis

The area between the 2 layers is a “jelly-like” substance known as the mesoglea.

Epi = skin

Gastro = digestive

Cnidarians3) One of two body forms – polyp or medusa

Cnidarians4) Nematocysts – specialized cells located on tentacles intended for capturing prey/stinging predators.

http://www5.pbrc.hawaii.edu/pcrl/News&Videos.html

Cnidarians5) Solitary or Colonial

*Sometimes secrete calcium carbonate “base” to rest on.

CnidariansMost cnidarian polyps can reproduce asexually. They are slow/sessile, so this is a means of recovering from attacks.

Cnidarian medusae have a complex development, and can only regenerate lost tentacles.

Reproduction

1) They cut a small piece of the glowing portion from “e”. 2) “a-d” shows the development of those cells. 3) “f” is what the cells grew into.

VERY FAMOUS STEM CELL RESEARCH PROJECT

CnidariansOther senses ocelli = eyespots on edge of bell (only detect light).

smell/taste = sensory receptors on bell and tentacles.

Cnidarians-Mouth = anus

-Simple digestive system tentacles pull food in and food is digested inside gastrodermis. Waste is expelled through the same hole that it came in.

Their gut has several folds to increase surface area for absorption of food, very similar to our intestines.

*Only in polyps*They contain mesenterial filaments. These can be extruded to “digest” other sessile organisms nearby.

CnidariansDeadly Irukandji jellyfish. Very rare off the coasts of Australia, but extremely potent venom

Discovery Channel Documentary http://video.google.com/videoplay?docid=-5244772188533526164&ei=OZlDS4ntKJ7cqALW_tzTCA&q=irukandji&hl=en#

Woman stung by jellyfish squirming due to immense pain all over body

Portuguese man-of-war

http://www.wkrg.com/florida/article/portuguese_man_of_war_invade_gulf_coast_beaches/12220/Jul-31-2008_12-21-am/

What would you do if you were

stung by a jellyfish?