Class Scyphozoa “true” jellyfish medusa & polyp body forms thick mesoglea

Class Scyphozoa- life cycle sperm egg ephyra Adult medusa strobila scyphistoma larva

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

Semaeostomae Jellyfish-- the typical jellyfish: corner of mouth drawn out into four broad gelatinous frilly lobes. Aurelia sp.

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 jellyfish About 3 dozen species almost all are tropical. medusa & polyp body forms thick mesoglea

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

velarial canals 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.

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 some contain zooxanthellae

Class Anthozoa some are colonial  colonies are formed of individual zooids some are solitary

Class Anthozoa- life cycle Sexual reproduction sperm egg larva

Class Anthozoa- life cycle asexual reproduction fission pedal laceration fission

Class Anthozoa Sea anemones

Class Anthozoa Soft Corals                                                   Sea pen Sea pansy

Class Anthozoa Stony Corals                                                                               

The Corals Make up the largest group of Anthozoa Colonial Secrete skeleton of calcium carbonate Cup shaped Polyp is fixed to this

Theca Sclerosepta

Fungia spp. Disk Corals

Phylum Ctenophora Ch 9

Characteristics of Ctenophora Diploblastic: with ectoderm and entoderm separated by a cellular mesenchyme. Biradial symmetry with the body axis being oral-aboral. Gastrovascular cavity with complete gut (mouth, gut, two anal openings). No type of bodycavity.

Ctenes of comb row

Ctenes of comb row

Comb Jellies Phylum Ctenophora are the larges animals known to rely primarily on cilia for locomotion.

Macrocilia

Life Cycle Gametes fuse in open water. egg sperm Gametes fuse in open water. Hermaphroditic adults release gametes. Pelagic cydippid larva.

Feeding Feed with specialized cells called colloblasts or lasso cells. A few species have cnidocytes.

Colloblasts on ctenophore tentacles

Figure 9.6 page 277 colloblasts

Figure 9.7 page 278 Kleptocnidae

Ph. Ctenophora Cl. Nuda Cl. Tentaculata ctene row Deiopea kaloktenota Pleurobrachia sp. Coeloplana sp. Cestus sp.

Bioluminescence Produce light using photocytes Located in the walls of the digestive system Appears that light is coming from comb rows NOT all produce luminescence

Big Picture The radiate phyla are the first (i.e. basal) Metazoans Most have a dimorphic life cycle Specialized structures the Cnidocytes Some such as corals secrete a calcium carbonate base Ctenophores produce bioluminescence