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 FREE-SWIMMING

• 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