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Cniderian lifecycle

Cniderian lifecycle. Jellyfish. Objectives. Be able to describe the general characteristics of a cniderian Describe how the nematocyst (cnidocyst) functions. Describe the lifecycle of the sea nettle Chrysaora quinequecirrha. Cnidarian Characteristics. Greek knide = nettle

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Cniderian lifecycle

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  1. Cniderian lifecycle Jellyfish

  2. Objectives • Be able to describe the general characteristics of a cniderian • Describe how the nematocyst (cnidocyst) functions. • Describe the lifecycle of the sea nettle Chrysaora quinequecirrha

  3. Cnidarian Characteristics • Greek knide = nettle • Radially symmetrical animals with a simple form, all with stinging capsules. • Species appear as polyps (sea anemones) or medusa (jellyfish), and often a species goes through both forms in its life cycle (jellyfish, hydroids). • Cnidarians live in the sea except for a few (e.g. hydra) that inhabit fresh water

  4. Stinging Capsules • These capsules are activated when chemically or mechanically stimulated. • Contains a cnidocyst (a dehydrated protein structure that resembles a harpoon) • Capsule activation caused the cnidocyst to swell resulting in ejection

  5. Stinging Capsule • The ejected cnidocyst penetrates the food item causing a sting • Sting is the result of an injected protein and may result in paralysis of food item

  6. Chrysaora quinequecirrha • One of several nettles that inhabit the Bay • Cnidocysts give a mild sting when encountered by swimmers with stings usually confined to sensitive skin • Year round resident but “jelly” only seen in summer months • Lifecycle has both polyp and medusa stages

  7. Lifecycle ofChrysaora quinequecirrha • Polyp form is sessile and attached to hard substrate (oysters, rocks, fallen trees) • Polyps are suspension feeders. They wave their feeding tentacles feeding mostly on plankton. • 1-2 inches (2-5 cm) in length • Polyps reproduce asexually by budding

  8. Lifecycle ofChrysaora quinequecirrha • Late Spring-Early Summer the polyps begin to enter the sexual phase of the life cycle • Polyps undergo strobilization • Strobilization is the pinching off of the terminal end of the polyp

  9. Lifecycle ofChrysaora quinequecirrha • Each piece of the strobilized polyp develops into an ephyra • Ephyra grow into the medusa (sexual stage) commonly described as “jelly fish”.

  10. Lifecycle ofChrysaora quinequecirrha • Medusa stage is the sexual stage • Male medusa release sperm, female medusa contains ova (eggs) • Fertilized eggs develop into a planula larva, which is ciliated and free-swimming. • Larva are part of the zooplankton for a short time then settle on hard substrate and become polyps

  11. Interactions • There are organisms that spend a lot of time associated with cniderians • Small crabs • Harvest fish

  12. References • http://www.discovery.com/area/nature/jellyfish/reproduction.html • http://ourworld.compuserve.com/homepages/BMLSS/Cnidaria.htm • http://animaldiversity.ummz.umich.edu/cnidaria.html • http://animaldiversity.ummz.umich.edu/cnidaria/scyphozoa.html • Hickman, C.P. and L. S. Roberts. 1994. Animal Diversity. Wm. C. Brown, Dubuque, IA. • Brusca, R. C., and G. J. Brusca. Invertebrates. 1990. Sinauer Associates, Sunderland, MA.

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