MARINE INVERTEBRATES:
STOP 2
PHYLUM CNIDARIAN - JELLYFISH
JELLYFISH INTRO
3 CLASSES
• SCYPHOZOA
• COMMON JELLIES
• HYDROZOA
• PORTUGESE MAN-OF-WAR
• OBELIA
• CUBOZOA
• BOX JELLIES
COMMON CHARACTERISTICS
• EVOLVED OVER 600 MILLION
YEARS AGO
• CONTAIN CNIDOCYTES –
STINGING CELLS
• WHICH EXPEL BARB-LIKE
NEMATOCYSTS
• MOST BLIND
• EXCEPT BOX JELLIES
• HAVE EYE CLUSTERS
COMMON
CHARACTERISTICS
• ALL ARE CARNIVOROUS
• SINGLE-OPENING DIGESTIVE TRACT (2
WAY)
• MOUTH AND ANUS ARE AT SAME
OPENING
• ECTOTHERMIC
• NO BRAIN, SKELETAL OR CIRCULATORY
SYSTEM
BODY PLAN
• VERY BASIC BODY PLAN
• RADIAL SYMMETRY
• ONLY TRUE ORGANS ARE GONADS
BODY PLAN
• 2 TISSUE LAYERS
• ECTODERM – OUTER COVERING
• ENDODERM – INNER LINING
• CONNECTED TO EACH OTHER BY
MESOGLEA
• NON-CELLULAR JELLYLIKE MATERIAL
PHYSIOLOGY
• HAVE A NERVE NET AND BASIC
RECEPTORS FOR IMPULSES TO MOVE
• OXYGEN TAKEN IN DIRECTLY
THROUGH TISSUES FROM WATER
COLUMN
• TENTACLES MAY BE METERS IN
LENGTH & CARRY POISONS THAT
CAUSE SEVERE PAIN OR DEATH
MOST DANGEROUS JELLYFISH
• WHEN THESE STINGER CELLS ARE TRIGGERED
THE INTERNAL PRESSURE BUILDS UP TO A
MASSIVE 2,000 PSI (136 ATMOSPHERES)
• WHEREUPON IT BURSTS, FIRING OUT A
TOXIN HARPOON
• THIS IS ONE OF THE FASTEST MOVEMENTS IN
NATURE AND QUICKER THAN A BULLET.
LIFE CYCLE
• HAVE BOTH ASEXUAL POLYPS
& SEXUAL MEDUSA STAGES IN
THEIR LIFE CYCLES
• ADULT MEDUSA STAGE
RELEASES EGGS & SPERM INTO
WATER
LIFE CYCLE
• FERTILIZATION PRODUCES CILIATED
PLANULA LARVA THAT SETTLES TO
THE BOTTOM, ATTACHES, & FORMS
TENTACLES
• NEW MEDUSA BUD OFF OF
REPRODUCTIVE POLYPS & FORM
ADULT JELLYFISH
LIFE CYCLE
• UNLIKE CORALS, SPEND MOST OF THEIR LIFE IN MEDUSA STAGE
• RANGE IN SIZE OF 2MM-30M LONG
Jellies
Corals
LIFE CYCLE
• MEDUSA FORMS ARE USUALLY FREESWIMMING
• BELL-SHAPED
ANIMALS WITH TENTACLES THAT
HANG DOWN AROUND THE
MOUTH
• THICK LAYER OF MESOGLEA FOR
SUPPORT
LION’S MANE JELLYFISH
LION’S MANE JELLYFISH
PORTUGESE MAN OF WAR