Holoplankton

Source: Wikipedia, the free encyclopedia.
parapodia[1]

Holoplankton are organisms that are

amphipods, krill, copepods, and salps, as well as some gastropod mollusk species. Holoplankton dwell in the pelagic zone as opposed to the benthic zone.[2] Holoplankton include both phytoplankton and zooplankton and vary in size. The most common plankton are protists.[3]

Reproduction

Holoplankton have unique traits that make reproduction in the water column possible. Both sexual and asexual reproduction are used depending on the type of plankton. Some invertebrate holoplankton release sperm into the water column which are then taken up by the females for fertilization. Other species release both sperm and egg to increase the likelihood of fertilization. Environmental, mechanical, or chemical cues can all trigger this release.[4]

Diatoms are single celled phytoplankton that can occur as individuals or as long chains. They can reproduce sexually and asexually.[5] Diatoms are important oxygen producers and are usually the first step in the food chain.[2]

Copepods are small holoplanktonic crustaceans that swim using their hind legs and antennae.[3]

Defenses

Because of their small size and sluggish swimming abilities, holoplanktonic species have made certain specialized adaptations and in some cases are equipped with special defenses. Adaptations include flat bodies, lateral spines, oil droplets, floats filled with gases, sheaths made of gel-like substances, and ion replacement.[3]

Zooplankton have adapted by developing transparent bodies, bright colors, bad tastes and

nematocysts on their tentacles that eject a coiled microscopic thread very rapidly. These threads penetrate the surface of their target and release a series of complicated, biologically advanced venoms. Their stings can be very dangerous, due in part to the number of vital systems affected.[7]

Sexual holoplankton

Copepods
Male and female copepod
Female copepod with eggs

See also

Sources

Australian Museum Online

References

  1. ^ Harvey, Edmund Newton (1952). Bioluminescence. Academic Press.
  2. ^ a b Anderson, Genny. "Marine Plankton". Marine Science. Retrieved 2012-04-04.
  3. ^ a b c d Talks, Ted. "Zooplankton". Marine Life/Marine Invertebrates. Retrieved 2012-04-04.
  4. ^ "Reproduction in the Plankton". Plankton. Retrieved 2012-04-04.
  5. ^ Pierson, James. "What is Plankton". Plankton. University of Maryland Center for Environmental Science. Retrieved 2012-04-04.
  6. JSTOR 2838739
    .
  7. . Retrieved 2013-09-19.