Download Kingdom Animalia

Kingdom Animalia
Phylum Cnidaria
Characteristics
 Radial
symmetry
 Diploblastic organization, 2
official tissue layers
 Gelatinous Mesoglea
 Gastrovascular cavity
 Nerve net
 Cnidocytes called nematocysts
Coiled
nematocyst
Reproduction/Life Cycle

Most alternate generations between
polyp and medusa form

Polyp – asexual, sessile, produce more
polyps (colonial) or medusae (pl.) by
budding…

Medusae – dioecious & free swimming;
fertilized larva (Planula) settles & forms a
polyp
Cnidarians
Feeding
 Use
nematocysts to stun or kill prey
 Tentacles
 Digested
bring food to mouth
in gastrovascular cavity
Support and Locomotion

Hydrostatic Skeleton (supported by
water)

Polyps – somersault, inchworm, walk
on their tentacles…

Medusae – swim, use water currents
Classification

Class Hydrozoa
 Most

Class Scyphozoa
 True

jellyfish
Class Cubozoa
 Cube

variable class
jellyfishes
Class Anthozoa
 Largest
class
Class Hydrozoa
Mostly marine, but only class with
freshwater members!
 Most display alternation of generations,
but polyps are dominant form
 Cnidocytes – only in epidermis
 Gametes released outside, from epidermis
 Medusae have a ‘velum’ (shelf-like lip),
used for jet propulsion

Hydra
 Freshwater
 Polyps
only,
no medusae
Obelia
Gastrozooid
(feeding zooid)
Gonozooid
(reproductive zooid)
Portugese Man-o-War, Physalia
 Colony
of polyps…
 Cannot
swim
(floats)
 Cnidocytes
are lethal
to small vertebrates
and dangerous to
humans
Class Scyphozoa
 “True
Jellyfish” – medusa dominant
body form
 Cnidocytes in the epi + gastrodermis
 Gametes
released into gastroderm,
then out of mouth
 Medusae
lack a velum
Moon Jellies, Aurelia
Stinging Nettle, Mastigias
Lions Mane, Cyanea
Record bell was 7 feet across, 120 ft. tentacles!
Class Cubozoa
 Medusae
are
cuboidal
 Polyps are
reduced or
absent
 Tentacles
hang from
corners
Ex. Sea Wasp (type of
Box Jellyfish)
Class Anthozoa
 Polyps
only, no medusae
 Gastrovascular
cavity is divided into
sections, with mesentaries
 Sexual
and asexual reproduction
 Sea anenomes, corals, sea fans
Sea Anemones
Corals
Sea Fans