Phylum Cnidaria

1
Phylum Cnidaria

• Cnidarians Include Hydras, jellyfish, sea
  anemones corals
• Radially symmetrical
• Acoelomate
• Two basic forms
• Polyp Cylindrical form which attach bases to
  substratum
• Medusa Flattened, mouth down version of the
  polyp. Moves freely

2
Forms of Cnidarians
3
Body Plan

• Basic Body Plan
• Has an outer epidermis
• Has an inner gastrodermis which forms a
  gastrovascular cavity
• Has a middle "jelly filled" layer called mesoglea

4
Cnidocytes

• Cnidarians are predators which have tentacles
  possessing batteries of special cells called
  Cnidocytes
• Cnidocytes contain special stining capsules
  called nematocysts.
• When triggered, these cells shoot out a discharge
  thread which can entangle and/or poison it's
  intended prey

5
(No Transcript)
6

• Reproduction
• Reproduction can occur sexually by fertilization
  of egg and sperm forming larvae.
• Reproduction can also occur asexually through
  budding
• 3 Major classes
• Class Hydrozoa Hydras
• Class Scyphozoa Jellyfish
• Class Anthozoa Anemones and corals

7
Class Hydrozoa The Hydras

• Polyp phase is dominant
• Generally microscopic
• Generally freshwater

8
Class Scyphozoa The Jellies

• Generally refered tro as jellies
• Medusa stage is dominant
• Come in a variety of forms
• Aggressive predators, and can be dangerous to
  humans

Jelly
Portugese Man-o-war
9
Class Anthozoa Anemones Corals

• Appear like plants but are animals.
• Polyp form is dominant.
• Corals build calcium shells to protect themselves
• Have symbiotic relationship with algae.
• Can build extensive masses which can form land
  masses.

Anemone
Coral Polyps
10
Coral Reefs
Clownfish living in An anemone