User:MarcelaCurcio/Marrus orthocanna

Marrus orthocanna is a species of pelagic siphonophore, a colonial animal composed of a complex arrangement of zooids, some of which are polyps and some medusae. Swimming independently in the mid-ocean, it lives in the Arctic and other cold, deep waters. It is a colonial creature that is born from a single egg which is fertilized. Later on, a protozoan form that eventually grows to form more duplicating members of the colony. It belongs to the order siphonophorae and the family Marrus. Other species in the family include the Marrus antarcticus, Marrus claudanielis, and Marrus orthocannoides.

Description
Like other siphonophores, Marrus orthocanna is a colony composed of a number of specialised zooids linked together by a long stem. At the front is the pneumatophore, an orange-colored, gas-filled float, the largest of which can reach estimated sizes of 5-10 centimeters in diameter  . Behind this is the nectosome, a region where there are a number of translucent nectophores with red, unlooped radial canals. These are bell-shaped medusae specialised for locomotion. When they contract, water is expelled which causes the colony to move. The coordinations of the medusae contractions enable the organism to swim forwards, sidewards, or backwards.

Biology
Marrus orthocanna can reach lengths of 2-3 meters long and the tentacles can extend fifty centimeters on either side.

History
The first siphonophorae to be described was the Portuguese Man O'War in 1758 by Carl Linnaeus. Until the 19th century, only three more species were described. However in the 19th century itself, 56 new species of siphonophorae were discovered and described. The family Marrus was not discovered until the early 20th century, by A.K. Totton, a British researcher who discovered new species during his lifetime. Marrus orthocanna itself was discovered by Paul Lassenius Kramp as part of the Godthaab Expedition of 1928, as they explored the area to the west of Greenland looking specifically at phytoplankton. A book about the expedition that detailed the Marrus orthocanna was released in 1942.