Do cnidarians have a nervous system?
Do cnidarians have a nervous system?
Abstract. Cnidarians have simple nervous systems and it was probably within this group or a closely-related ancestor that nervous systems first evolved.
How do cnidarians impact humans?
All cnidarians have the potential to affect human physiology owing to the toxicity of their nematocysts. These, and even normally innocuous species, can be deadly in a massive dose or to a sensitive person, but the only cnidarians commonly fatal to humans are the cubomedusae, or box jellyfish.
What is unique about cnidarians?
All Cnidaria are aquatic, mostly marine, organisms. They all have tentacles with stinging cells called nematocysts that they use to capture food. Cnidarians only have two body layers, the ectoderm and endoderm, separated by a jelly-like layer called the mesoglea. Most Cnidarians have radial symmetry.
What are the two stages in the life cycle of cnidarians?
Cnidarians all have a life cycle of two forms. One is a free-swimming jellyfish medusa stage and the second is an attached polyp stage.
Do anemones have a medusa stage?
As cnidarians, sea anemones are related to corals, jellyfish, tube-dwelling anemones, and Hydra. Unlike jellyfish, sea anemones do not have a medusa stage in their life cycle. Sea anemones also breed asexually, by breaking in half or into smaller pieces which regenerate into polyps.
How do cnidarians protect themselves?
Cnidarians defend themselves and catch prey using their tentacles, which have cells called cnidocytes at their tips.
Which cnidarians are most likely to reproduce in two stages?
Answer: Jellyfish and Portuguese man-of-war are the correct answers.
What are the stinging cells used by cnidarians to stun their prey?
Nearly all (about 99 percent) cnidarians are marine species. Cnidarians have specialized cells known as cnidocytes (“stinging cells”) containing organelles called nematocysts. These cells are concentrated around the mouth and tentacles of the animal and can immobilize prey with toxins.