Class Scyphozoa

• “true” jellyfish• medusa & polyp body forms• thick mesoglea

Class Scyphozoa- life cycle

eggsperm

larvascyphistomastrobila

ephyra Adult medusa

Jellyfish Diversity

Jellyfish are a major ecological significance of the plankton. Found in all oceans and range from the sea surface to the abyss. There are about 200 species world wide.

Jellyfish Diversity

Aurelia sp.

Semaeostomae Jellyfish-- the typical jellyfish: corner of mouth drawn out into four broad gelatinous

frilly lobes.

Cyanea capillata the Giant Jellyfish or Lion's Mane Jellyfish can grow to be one of the largest of all jellyfishes. Its disc-shaped bell can be over 1 meter across and its trailing tentacles can reach more than 10 meters in length.

Primitive jellyfish: Stauromedusae

Jellyfish Diversity Primitive jellyfish: Stauromedusae; small sessile individuals that develop directly from benthic planula larvae.

Can change locations, but normally attached with stalk and adhesive pad to solid objects like kelp and rocks.

Rizostomae jellyfish: lack a central mouth, instead they have many suctorial “mouths”

Cassiopea: a small tropical jellyfish is unusual among jellyfish.

It lies on the bottom in shallow waters, with its mouths and tentacles oriented upwards. Its mouth is much reduced, and is not much used.

Instead, the jellyfish gets most of the nutrition it needs from symbiotic dinoflagellates (protists) which live inside its body tissues.

Rhizostoma octopus

Class Cubozoa: Sea wasps and box jellyfishAbout 3 dozen species almost all are tropical.

medusa & polyp body forms thick mesoglea

Unfrilled bell margin drawn inward to form a velum-like structure.

The velarium is at least partly responsible for the great speeds with which cubozoans are able to swim.

Velarial canals are extensions of the gut and they are important in telling one species of cubozoan from another.

velarial canals

Manubrium: a tubular extension where the mouth is.

Cubozoan Sensory Structures

Sensory structures called rhopalia.

Cubozoan Sensory Structures

cubozoans have eyes.

The larger regions actually contain lenses, corneas, and retinas.

Nematocysts are concentrated in rings on the tentacles of cubozoans.

Predominantly two species responsible

• The Box Jelly Chironex fleckeri

• Irukandji Carukia barnesi

The Box Jelly Chironex fleckeri

The Box Jelly Chironex fleckeri

Box Jelly Chironex fleckeri

• Box jellies or sea wasps are thought to be responsible for about 65-100 deaths over the past 50 years in Australia.

• The tentacles can be up to 10 feet long.

• In Australia twice as many people die annually from box jellies as from sharks.

• The toxin of most cubomedusan jellies is more potent than cobra venom.

Irukandji Carukia barnesi

Stings have been recorded from Australia, and a similar syndrome has been described elsewhere in the Pacific.

Every summer, more than sixty people are hospitalized with this potentially fatal syndrome.

Irukandji Carukia barnesi

• The initial sting of the jellyfish is usually not very painful.

• But about 30 minutes after being stung, the person starts to have a severe backache or headache and shooting pains in their muscles, chest and abdomen.

• They may also feel nauseous, anxious, restless and vomit. In rare cases, the victim suffers pulmonary aedema (fluid on the lungs) which could be fatal if not treated.

Cubozoan Life Cycle

• Some species of cubozoans appear to pair up, male with female, in order to mate.

• The male puts his tentacles into the bell of the female and appears to pass packets of sperm. At least one species has been observed in large mating aggregations.

Cubozoan Life Cycle• Fertilization takes place

inside the females. In some species the fertilized eggs are released into the water column where they develop into planulae, while in others development into planulae occurs inside the female.

Cubozoan Life Cycle

• The polyps can move around, and they frequently bud off additional polyps.

Cubozoan Life Cycle

• During metamorphosis, the polyp tentacles are resorbed and four new tentacles and four rhopalia are formed. With a couple of contractions, the entire individual becomes detached and swims away as a juvenile medusa.

Class Anthozoa

• polyp body form ONLY • all marine

Class Anthozoa

• some are colonial colonies are formed of individual zooids

• some are solitary

Class Anthozoa- life cycle

eggsperm

larva

Sexual reproduction

Class Anthozoa- life cycle

asexual reproduction

fission

pedal laceration

fission