Calanoida
Sars 1903
Taxonomy
| Phylum | Arthropoda |
| Subphylum | Crustacea |
| Class | Maxillopoda |
| Subclass | Copepoda |
| Order | Calanoida |
Description
- Includes 43 families and approximately 2000 species (marine and freshwater).
Distinguishing characteristics
- Long, usually slender body.
- Long antennules.
- Geniculate antennae in males.
- Gymnoplean tagmosis (boundary between fifth pedigerous somite and genital somite).
- Fifth leg biramous .
Distribution
- Worldwide.
- Animals in this group usually outnumber all other taxa in the marine zooplankton.
Ecology
- Drift in water column often hanging motionless.
- Locomotion by slowly sinking or by swimming smoothly in circles or spirals by rapidly vibrating the second antennae.
- Can respond to danger quickly by upward darting jumps carried out by the thoracopods.
- Many species have been observed to undergo diel vertical migration; feeding at the surface layers at night and migrating deeper during the day.
- Mostly herbivores.
- Suspension feeders; continuous feeding current created by head appendages.
- Larval development metamorphic. Embryos carried in single or paired sacs. Eggs can also be deposited externally. Long, usually slender body.