Lab 5- Stimulus -Response Behaviors in Cnidarians

Sensory structures

Oceil (light perception)

Statocytosis (gravity perception)

Sea anemones experiment

• Responses to tactile stimuli

• Response to food particles (solid and liquid)

• Tactile & Chemical stimuli (mucus)

Sea anemone response to stimuli : Rod, solid food, and liquid food

Touch with rod: contrasts or grips tight

Large food:  Tenacles fold in and grabs food

Liquid food:  Tenacles slowly or barely fold in 

Polyorchis (jellyfish): Shadow response

• responds to rapidly decreasing light intensities with rapid swimming contractions

Gonionemus Vertens (Jellyfish) behaviors 

• Feeding- involves contraction of prey-carrying tenacles 

• Somersaulting- inversion of medusa as it strikes the water surface 

• Tentacle anchoring- refers to the attachment of the tentacles to the substrate by the anchor pads 

• Swimming- due to contraction of the swimming muscles 

Stereotyped behavioral patterns

• Present in some form in the behavioral repertoire of all hydromedusa (a small, jellyfish-like organism that is part of the life cycle of certain hydrozoans)

• Are such sequences for which the probability that they will occur is high

Behavioral patterns

Probabilistic sequence of behavioral acts or simultaneous clusters of behavioral acts.