Anemones and corals belong to Class Anthozoa (Phylum Cnidaria). Though not common at Axial, a few different species (currently not identified) have been observed.
Sea anemones are members of the diverse Order Actiniaria, and are commonly found around the world’s oceans. Their shape generally includes a central, cylindrical body (or column) with a number of tentacles reaching outward in a radial pattern. While they are mostly sessile, many are known to be capable of some movement, with some species even floating freely through the water column. Although several anemones are known to feed on free-floating particles, the majority are predatory. Their tentacles can be used for hunting and for defense; they sting their prey with a mix of neurotoxins in order to stun them, using stinging cells called nematocysts. Sea anemones have a novel method of body support involving their gel-like mesoglea, which allows the body to deform without permanently losing shape or structural strength. Anemones are found all over the world’s oceans, in practically every environment known to man. On Axial Seamount, they have been observed on lava rocks and in the sediments at Axial’s base. Size of those that inhabit Axial is less than 20 cm.
Corals are found throughout the world’s ocean, mostly in tropical waters. The majority of species, especially those found in shallow waters, have a symbiotic relationship with phytoplankton called zooxanthellae through which they obtain their energy. At the depths of Axial Volcano, however, there is no sunlight and therefore no fuel for the photosynthetic zooxanthellae to survive. Species of corals living at these depths live independently and get their food from zooplankton, crustaceans, and krill brought to them by oceanic currents. They sting their prey with nematocysts attached to small tentacles. Without the zooxanthellae symbiont, these deep sea corals do not grow as fast as their shallow water counterparts. Because they are sedentary organisms, they must live in nutrient rich waters. Due to this, many deep sea species are found near pockmarks in the seabed, which are formed by expulsion of nutrient rich gas deposits within the sediment. The size of these corals vary from tiny polyps, only millimeters across, to large structures, towering tens of meters tall. Most must be attached to hard substrates, but some species such as sea pens can use the sediment for habitat.
References:
http://en.wikipedia.org/wiki/Sea_anemones
http://eol.org/pages/1747/overview
Judd, A. and Hovland, M. (2007). Seabed Fluid Flow. Impact on Geology, Biology, and the Marine Environment. Cambridge University Press.
https://en.wikipedia.org/wiki/Deep-water_coral#Growth_and_reproduction
To date, three different anemone species and 1 deep coral species have been imaged at Axial.
Unknown Anemone 1
This species has been seen clinging to lava rocks on more than a few occassions. It is often this pale pink to salmon color, with numerous, short tentacles. It measures approximately 10 cm.
Unknown Anemone 2
This small anemone was found at Axial’s base, inhabiting the soft, pelagic muds. Its body, or column, is short, with long, translucent white tentacles.
Unknown Anemone 3
This small, orange-hued anemone is quite squat and nearly flat, with short tentacles. It may be of the type referred to as a Jack-O-Lantern Top.
Unknown Coral 1
Only observed once, this fan-like soft coral was clinging to pillow basalts near to the base of Axial Seamount. Corals found in the deep sea are colonial, with tiny individuals known as polyps living among the structure. These polyps are similar in morphology to anemones, but they live within a structure called a corallite. Deep sea corals are suspension feeders, and do not have the symbiotic algae (Zooxanthellae) living among their tentacles, since there is no light for the algae to photosynthesize.