The coronate scyphomedusae include some of the most stunning of all
the jellies. Within Monterey Bay this group is nearly entirely found only in deep
midwater habitats, so you are not likely to see one at the surface. Among
the coronates, Periphylla periphylla
is the only species known to be
holoplanktonic without any kind of sessile polyp stage. It also lacks the
ephyra stage and does not produce planula larvae like other scyphozoans. Like other
has a groove in the exumbrella (the coronal groove) that
probably provides some flexibility to the relatively stiff bell. The bell may reach
up to 20 cm in height, has 16 lappets around the margin, and is topped off by a conical
apical tip. The tentacles are stiff and 12 in number, and often held in an upward
position. They form groups of three that alternate with the 4 rhopalia.
Through the transparent bell is seen a strikingly beautiful deep reddish-brown stomach
area. Presumably the brilliant pigmentation in this and other deep-water jellies
masks the light produced by ingested bioluminescent prey. Periphylla
vertical migrator, rising to shallower depths at night to feed on copepods and other
crustaceans. It is found throughout the worlds oceans, typically below 900 meters in
Monterey Bay and as deep as 7000 meters in other areas, but potentially at the surface in higher latitudes. Periphylla
may reach much larger sizes in Antarctic waters compared to temperate latitude
populations. This species may be the most abundant, widely distributed deep-water
scyphozoan, and is commonly collected in midwater trawls by scientists.
All photographs © David
Wrobel and may not be used or copied without permission!