Cnidaria Flashcards
Name the 8 traits of the phylum Cnidaria
- Diploblasty - 2 distinctive germ layers: ectoderm and endoderm
- Incomplete gut - only one hole. Has a GVC
- Epitheliomuscular cell - allows cnidarians to move. Not really muscles, but they’re like skin cells and are contractile
- Radial symmetry
- Net-like nervous system
- Cnidae
- Polpys - body plans. The medusa states are only found in medusazoa
- Circulation - GVC. They exchange gas by diffusion
3 synapomorphies of Cnidaria
- Epitheliomuscular cell
- Cnidae
- Polyps
Cnidae
Located inside a structure called cnidocyte. The nematocyst will fire a harpoon in the organism
Nematocysts
Located inside the cnidocyte cells on the tentacles. It penetrates the prey and releases toxins
Spirocysts
Sticking spaghetti noodles to entangle the prey. Specializes in animals with exoskeletons
Cnidaria major subgroups
Anthozoa - sea anemones, like corals
Medusazoa - can move and swim. Hydrozoa and Scyphozoa belong to this group
2 taxa of Medusazoa
Hydrozoa - hydroids, hydras. Prominent polyp stage where some are solitary and some are colonial. The polyp stage gives rise to an asexually produced medusa stage called the hydromedusa, which reproduces sexually. Has a mesoglea
Scyphozoa - considered the “true” jellyfish and has a prominent medusa stage. Has a mesenchyme
Enzymatic gland cells
Releases proteins/enzymes in the GVC to breakdown food
Mucus gland cell
Added layer of protection on epidermal cells
Operculum
The lid of the cnidocyte
Cnidocil
The trigger of the cnidocyte. When something brushes against it, it triggers the cnidocyte and shoots out the nematocyst
Hydra
Genus of hydrozoans. Solitary polyp freshwater. Experiments have been done to hydras that show that they have the ability to re-fashion its cells as adults. It can turn its epidermis to the gastrodermis and vice versa
Gonad in Hydra
Ectodermally derived in Hydra
Obelia
Genus of hydrozoans. Hydroids are examples. They are colonial and marine. They look like flower bouquets
Gastrozooid
Subcomponent of the obelia colony. Focused on feeding
Gonophore
A structure that will develop into a medusa
Gonozooid
For reproduction to build and bud Medusa
Perisarc
Made of chitin. Surrounds the whole colony of obelia
Dactylozooid
Used for defense. Extra long. Usually filled with nematocyst
Coenosarc
Hollow fluid-filled space that surrounds the colony that connects the zooids of a hydroid colony
Physalia
Genus of hydrozoans. Are considered the floating colony. An example is siphonophora
Pneumatophore
Covered in perisarc. A gas-filled float that helps Physalia float
Clonal
Genetically identical. Not integrated at the tissue level. Physically separated
Colonial
Genetically identical and connected at the tissue level
Acrorhagi
Located around the collar of an anemone. Filled with nematocysts to defend