Nest guarding

While we're on the subject, I'll share this short video.  Many sunfish (in the Family Centrarchidae) also build and guard nests.  Often, it's the little males that pull guard duty.  That's the case in the longear sunfish, Lepomis megalotis.  While sampling a local stream, we watched this little guy and his buddies working hard guarding eggs from marauding bluegills.

A couple of stickleback stories...

The three-spined stickleback, Gasterosteus aculeatus, has been a heavy hitter in ichthyological research for decades.  Niko Tinbergen, who would share a Nobel Prize in 1973 with Karl von Frisch and Konrad Lorenz, helped create the field of ethology with his pioneering observations of stickleback courtship behavior.  I encountered sticklebacks during my time in Oregon and Alaska, but not since.  They're widespread across the Northern Hemisphere, but being coldwater guys they aren't typically found south of North Carolina on the Atlantic Coast.  That's too bad - they're great little fish for number of reasons.  They show a wealth of morphological diversity, making them ideal for the study of adaptation.  Although they're anadramous, typically spawning in fresh water but maturing in the sea, they can live out their lives in fresh or salt, and show a remarkable ability to deal with a wide range of salinities.  It's in their behavior, most notably their spawning behavior, that's been most heavily examined.  Males invest a lot of time and energy in buiding nests, to which they entice females and then guard ferociously until the eggs hatch.

Stickleback nest

Well, it appears that European sticklebacks have had a tough spring.  Rivers there are swollen from heavy rainfalls, and currents are higher than normal.  This means that male sticklebacks there are having to put in extra duty to make sure their nests don't get lost in the flood.  The nests are constructed of materials that the fish can find in the river, sand and pieces of plant material.  The building materials, though, are cemented together with "spiggin", a glycoprotein glue produced by the male stickleback.  Spiggin is produced during the breeding by hormonally-influenced epithelial cells in the kidneys.  According to results published in Avian Biology Research, this high-flow year is forcing the fish to produce more spiggin than normal - a task that could potentially draw energy away from other important processes.  Thus far, the fish seem to be holding their own - another indication of a fish that seems to be a master of adaptation. 

Shoaling sticklebacks (photo by
Steve Thomas)

While we're talking about sticklebacks...  Another of their interesting behaviors is the tendency of non-Researchers at the Konrad Lorenz Institute of Ethology offered individual sticklebacks the opportunity to join two schools of fish, one made up of siblings and one made up of unrelated individuals.  The sibling group was in some cases made up of familiar fish, and in other cases made up of relatives with which the test fish was unfamiliar.  The test fish chose to join the sibling group whether they were familiar with the members or not.  The researchers then extended the experiment, giving the sticklebacks a choice between groups of familiar and unfamiliar relatives.  Surprisingly, the test fish showed no preference.  In this case, the kin preference is driven by something other than familiarity.
breeding fish to gather in groups or shoals.  In the formation of these shoals, sticklebacks  prefer the company of relatives.  The basis for that preference has been uncertain - is it innate based on some sort of olfactory cue that identifies related individuals, or is it developed by interactions during the fish's life history.  

New Caribbean blenny

Haptoclinus dropi

From Zookeys, this report of a new haptoclinid blenny.  Haptoclinus dropi is tiny, about an inch long, and has the unusual four-sectioned dorsal fin of the other members of the genus.  It was discovered in the southern Caribbean at depths of about 160 meters as part of the Smithonian's Deep Reef Observation Project using the manned submersible Curasub.  The Curasub, which operates out of Substation Curacao, normally operates carrying tourists to depths of over 300 meters.