Invert Lab Exam Flashcards
Lion’s Mane jellyfish
Cyanea capillata
Characteristics
- lacks skeletal structure
- specialized organs for respiration or excretion
- organized tissues
- large umbrella-like bell and gelatinous tentacles
- star pointed bell size around 2ft in diameter with their tentacles trailing 28ft below (larger in colder regions)
- extremely sticky tentacles - 8 groups of over 20
- marine
Reaction to their surroundings
- absence of a nervous system, react to their surroundings through a loose network of nerves, located epidermis
- The nervous system is a decentralized network (‘nerve net’)
Reproduction
-one year life cycle
-two distinct formations
-four distinct stages
-fertilization process…males expel sperm through the mouth and fertilize a nearby egg, on the oral arms of the female.
-Then.. zygotes develop into ciliated planula larva
…Once ready, larva fall from oral arms and settle on ocean floor to develop into polyps
… scyphistoma, or fully grown flowering polyps (replicate by budding), that transform into strobila (strobila polyps), which are actually stacks of ephyra, which are the actual jellyfish…. polyps reproduce asexually, which break off and grow into medusas, a mature jellyfish
Two distinct formations
- young asexual polyp
- matured sexual medusa
four distinct stages
- larval stage
- polyp stage (scyphistoma into strobila polyp)
- ephyrae stage (clone of polyp)
- medusa stage
habitat
- Prefer cooler waters, found north of 42°
- pelagic for most of their lives, seek refuge in shallow, sheltered bays near the end of their lives
- open ocean at depths no greater than 20m, shelter animals from predators, including shrimp, medusafish and butterfish
Predators and prey
prey include plankton, moon jellyfish, small fish and ctenophores
- Cnidocyte (stinging cells) have nematocysts on their tentacles, which pierce, sting and entangle prey
- Small sensory hairs (cnidocils) near the nematocysts are sensitive to vibrations in the water. (discharged in response to chemical or physical stimuli).. Any prey swimming past can trigger the nematocyst which shoots out the barb. This penetrates the prey’s outer covering and injects it with venom. The prey is then moved to the mouth by a tentacle.
- Relative inability to control their direction, easily preyed upon by sea turtles, large fish, and various sea birds.
Digestion
- Once captured, prey pulled in towards the mouth, underneath the bell, through the retraction of the jellyfish’s tentacles
- Initial ingestion takes place in the gastrovascular cavity, though digestion is completed intracellularly
- excretion done through diffusion (higher to lower concentration)
In respect to humans…
- Painful stings, but generally not fatal to a healthy human
- sting will likely develop a rash that will fade over a few days.
- ability to foul up fishing nets
- generally regarded as pests by humans.
- stable populations, no current conservation implemented in the protection of this species
- predation on fisheries
- aesthetics
- medicines
Taxonomy
Phylum: Cnidaria Class: Scyphozoa Order: Semaeostomeae Family: Cyaneidae Genus: Cyanea Species: capillata
What type of symmetry?
-Medusa have radial symmetry
Uni or multicellular?
Multicellular - but no organs
- internal cavity used for respiration (done through diffusion)
- gastrovascular cavity (a “stomach”) with a mouth
- do not have an anus
- They possess a body wall with two layers (the ectoderm, (epidermis) and the endoderm, (gastrodermis)) separated by a jelly-like layer called the mesoglea - DIPOBLASTIC
cnidocyte
stinging cells
nematocysts
- structure within cnidocyte
- coil, thread like stinger - when triggered, uncoils and goes straight
