|Snowflake moray. Image - J. Randall|
The snowflake part of the name is easy to understand, although a little odd for a tropical fish. The name is reminiscent of those white winters my kids have never experienced. Hawaii winters are mainly rainy with temperatures all the way down into the 60's, which seems arctic to us. My wife is currently using two comforters on the bed since it is so "cold" in December.
|Image J. Randall|
The scientific name is Echidna nebulosa. The "nebulosa" part is from the latin for "cloud." Just think of astronomical nebulae, clouds of gas and dust with stars showing through.
|Reflection nebula, credit J-C Cuillandre, CFHT and G. Anselmi, Coelum Astronomia|
I have no idea if this story was in the mind of the scientist who originally named this group, but who could ask for more for a moray eel?
Snowflake morays start out as females and then become males later in life. Sex change in reef fishes is a fairly common and occurs in parrotfishes, wrasses, gobies and others. In parrotfishes the change from from female to male includes a dramatic shift in color. No such change occurs in the snowflake morays, although a paper in the Japanese Journal of Ichthyology documented sharper teeth in the male stage.
In general, most moray eels have extremely sharp teeth, often backwards pointing for capturing and eating live fish. Snowflake morays, on the other hand, have conical or pebble shaped teeth that are much more suitable for eating the crabs, shrimps and such that make up the majority of their diet. The teeth break up the tough exoskeletons of the eels' prey before it is swallowed. Their skull's compact shape is actually set up to deliver more force to their teeth for crushing than is found in the longer, narrower skulls of their fish eating relatives (Mehta, 2009).
|Snowflake moray teeth middle left. Image Mehta 2009.|
However, snowflake morays are not picky. They will eat fish as well as crustaceans if they can get them. Most reports suggest that they take small fish, but Miller, 1989, showed that they will use knotting as a strategy as well. This is a technique for dealing with prey that are too large, difficult to extract, or are not pointed the correct way for swallowing. The moray simply ties itself into a knot and then draws the prey through the knot. This will realign the prey, extract it, or tear a section out. You would think that a snowflake moray couldn't do much damage with its small teeth, but with its strong jaws, it is capable of tearing chunks out of other snowflake morays (see J. Hoover's book for one account). Perhaps the sharper teeth of the adult males are useful for aggressive encounters with morays of their own species, or reflect their ability to take larger fish and other prey as they grow.
While most reef fish use some form of the incredibly fast suction feeding method, gaping their mouth open and literally vacuuming prey in, moray eels are ram feeders. They strike, grasp, and once they have a hold with the outer jaws, the inner and independent pharyngeal jaws (inner teeth plates) grab hold and work the prey in (see image below). For those that remember the movie Alien, it is hard not to see parallels here. In snowflake morays, the inner jaws help crush and process the food. Ram feeding, although slightly slower than suction feeding at the start, may be particularly useful in the holes and crevices within which the snowflake moray hunts. The head can move while striking, allowing more variable response and perhaps better realignment and success of prey capture during the strike process (Mehta and Wainwright, 2006).
|Illustration via R. Mehta, NSF|
Finally, lets finish with a paper that includes Brian Bowen from HIMB's ToBo Lab. Some types of fish are found everywhere from Hawaii to Australia to the Red Sea. They are somehow able to get around and have one global population. Others are found in only a few places or even in just one island chain. Hawaii's endemic fishes fall into the latter category. They really don't get around much at all.
One factor that relates to whether a fish is common over a large area or not is the fish's habitat preference. If a fish has a habitat that is "patchy", or not continuously connected, this can lead to barriers to the spread of the species (that particular type of fish). Consider the snowflake moray; they are found in shallow areas with reef, rock or boulders. Sandy beaches will break up their habitats, deep water between islands will break up their populations, and long ocean distances will be a barrier to the adults as well. Other moray eels that can range from shallow to deep water should have more connectivity and range than the snowflake morays.
|Leptocephalus larval stage|
So the next question is, will the long planktonic stage trump the patchy and separated habitat preferences of the adults? Will snowflake moray populations Indo-Pacific wide show just as much genetic connection as morays that are more generalist in their habitat selections? Based on recent work by Reece, Bowen, Smith and Larson, 2011, the answer is yes; the long plantonic stage is a stronger influence than a 5-fold difference in habitat availability for adults.
|Image J.E. Randall|
J.E. Randall. Reef and Shore Fishes of the Hawaiian Islands. Sea Grant College Program. University of Hawaii. Honolulu. HI pp. 80-81.
J.P. Hoover. 2008. The Ultimate Guide to Hawaiian Reef Fishes, Sea Turtles, Dolphins, Whales and Seals. Mutual Publishing. Honolulu, HI