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Home , Carukia, Cnidaria, Cnidocyte, Ctenophora, Irukandji jellyfish, Planula

Cnidaria & Characteristics - Include Hydras, , sea anemones & -Radially symmetrical

Two basic forms: : Cylindrical form which attach bases (Sessile) Hydras, anemones Medusa: Bell-shaped, down version of the polyp. Moves freely Polyp

Marine

Freshwater Medusa Body Plan

• They have tissue layers • Outer layer of cells - the • Inner gastrodermis, which lines the gut cavity or (gastrodermis secretes digestive juices into the gastrovascular cavity) • In between these tissue layers is a noncellular jelly-like material called Movement &

• The cnidarian body is capable of some kind of coordinated movement • Both the epidermis and the gastrodermis possess cells arranged in a loose network - (plexus), which innervate primitively developed muscle fibers that extend from the epidermal and gastrodermal cells • Stimulus in one part will spread across the whole body via the network

Movement & Nervous System Nutrition

• Cnidarians are carnivores • hydras and corals consuming • sea anenomes & jellyies consuming small & clams • Use to capture prey and direct it toward the mouth • Digested in the gastrovascular cavity where gland cells secrete that digest prey. • The gastrovascular cavity exists as 1 opening for food intake and the elimination of waste. IN one cavity; OUT the same cavity • There is no system of internal transport, or excretion; all these processes take place via

Cnidocytes

• Prey capture is enhanced by use of specialized stinging cells called located in the outer epidermis. • Each has a modified - cnidocil, and is armed with a stinging structure called a nematocyst. • The undischarged nematocyst is composed of a long coiled thread • When triggered to release, either by touch or chemosensation, the nematocyst is released from the cnidocyte and the coiled thread is inverted • Some nematocysts function to entangle the prey; others harpoon prey and inject a paralyzing Cnidocytes

• Nematocyst Animation: Feeding Tentacles – http://vimeo.com/37431528

• Nematocyst Animation: Fighting Tentacles – http://vimeo.com/37432287

Portuguese Man O' War

Box Jellyfish

Reproduction

• One of the most amazing adaptations is the ability of some cnidarians to regenerate lost parts or even a complete body • is common with new individuals being produced by budding • Sea anenomes engage in a form of asexual reproduction called pedal laceration (pieces break off and regenerate new clones) • Fertilization is external, with the zygote becoming a elongated, ciliated, radially symmetrical - larva

Life Cycle

Cnidarian : The Hydras

• Can be found in freshwater; most are marine • Live solitary or colonial • cycle includes both asexual polyps and sexual medusa stages; or neither or both. • Freshwater hydras are found in ponds and streams • Mouth opens to the gastrovascular cavity • The life cycle is simple: and are shed into the and form fertilized eggs; planula is by passed with eggs hatching into young hydras • Asexual reproduction via budding – Budding were bud stays attached to main stalk. Adding more and more. Class Hydrozoa:

Colony: crocea Class Hydrozoa: Hydra

Colony: Tubularia crocea Class Hydrozoa cont.

Life Cycle of • Gonozooids release free swimming medusae • Zygotes become planula larvae, which eventually settle to become polyp colonies

• The medusae of hydroids are smaller than those of (C. ) • Also, the margin of the bell projects inward forming a shelf-like velum Class Hydrozoa Cont…

Portuguese Man O' War • Actually a floating colony of four different polyps which are connected by tissues. • Body polyp consists of a nitrogen- filled bladder which floats on top of the water. • Reproductive polyp • Feeding polyp • Defense polyp - tentacles that are typically 10 m (30 ft) in length but can be up to 50 m (165 ft), which contain toxic nematocysts. Class Scyphozoa: The Jellies

• Typical “Jellyfish” • Umbrella-shaped bell (medusa) and trailing tentacles. The bell can pulsate for locomotion, while stinging tentacles can be used to capture prey. • Contain massive amounts of mesoglea (95-96% water) • Bell – • Manubrium - stalk-like structure hanging down from the centre of the underside, will reach out for prey then grabs it with its mouth • Velum – shelf-like inward fold that increases water jet flow • ( gravitational detectors or balance sensory ) • Ocelli – photoreceptor cells • Hydrostatic – based on water filling up cavaties. • Radial Canal – aid in moving food from • Rhopalia - sensory structors • Gonads - sexual gland • Tentacles – • nematocysts • ~+500 million , oldest tissued .

Class Scyphozoa: The Jellies

Scyphozoan Life Cycle -

• Gametes develop in gastrodermis of gastric pouches; eggs and sperm are shed through mouth • Fertilized eggs develop into a planula larva; settles on substrate and develops into a polyp - scyphistoma • Scyphistoma produces a series of polyps by budding - strobila • The polyps undergo differentiation and are released from the strobila as free swimming ephyra • Ephyra matures into an adult jellyfish Class Cubozoa: Box Jellies

• Similar in form to scyphozoans • Box-shaped medusa allows it to move more rapidly than other jellyfish. • Four corners of the bell contains a cluster of 15 tentacles up to 3 meters long covered with millions of cnidocytes • Four -clusters with twenty-four , complete with , and lenses. • Tests have shown that they have a limited memory, and have a limited ability to learn • Diet that consists of fish, worms, and . • Mostly found in the Indo-Pacific, but some are found many other areas of the world • fleckeri -One of the most venomous creatures in the world. • Strong toxin, causes immediate, extreme pain • Death can occur 3-20 min after a sting

Class Cubozoa:

• barnesi • Extremely venomous jellyfish that inhabit marine of Australia • Bell about 5 mm - 10 mm wide and four long tentacles, which range in length from just a few centimeters up to 1 meter. • Nematocysts are in clumps, appearing as rings of small red dots around the bell and along the tentacles • is very powerful, 100 times as potent as that of a cobra

Class : Anemones • Do not have a medusa stage in their development. ONLY Polyp • Instead, they release sperm and eggs that form a planula, which attaches to some substrate on which it grows • They attach to shells, rocks, timber, etc. by pedal discs; some burrow in mud or . • Most anemones can glide slowly on pedal discs; some can swim with limited ability. • A crown of tentacles (nematocysts) surrounds the flat oral disc. • A slit-shaped mouth leads into a . • The siphonoglyph is a ciliated groove that creates the water current into the pharynx. • Currents carry in oxygen and remove wastes, and maintain fluid pressure for a . • When in danger, water is rapidly expelled through pores as the anemone contracts to a small size. • Most harbor symbiotic ; some have a mutualistic relationship with clown fish.

Class Anthozoa: Anemones Class Anthozoa: Corals Scleractinian Corals •Also known as true or stony corals. •They are miniature sea anemones that live in calcareous cups they have secreted. •A sheet of living tissue forms over the surface, connecting all gastrovascular cavities. Coral Reefs •Living and are limited to the top layer above the carbonate Coral Polyps deposits. •These corals require full of seawater and warmth and light, limiting them to waters between 30 degrees north and south. Fringing Reefs Barrier Reefs Atolls

Phylum Ctenophora: Comb Jellies

• 8 comb rows • Have colloblasts: sticky ends that are used to capture prey • Catch food with tentacles • Bioluminescent • All marine • Most are pea-size to golf ball-size