his necessary trick
for romance or rivalry?
the artists’ signature
Whenever I go to the grocery store I am amazed at the numerous assortment of eggs; free-range, AA, pasteurized, organic, brown, white, omega-3 enriched and vitamin-enhanced. I feel a similar (actually, a remarkably amplified) wonderment when I am reminded that there are 2000-3000 kinds of cichlid fishes!
What do you get when you combine eggs and cichlid fishes? Egg-spots!
One of among hundreds of curiosities of this fascinatingly diverse group of fishes is egg-spots or egg-dummies. Unique to haplochromines, egg-spots resemble fish eggs in size, shape (circular) and colour (yellow-orange-reddish), and are located on the male cichlid’s anal fin, a relatively unexplained fin in comparison to others (e.g. caudal, pectoral).
It’s important to know that haplochromines are mouth-brooders; a female lays her eggs and picks them up in her mouth, then the eggs are fertilized and she rears the progeny in her mouth. How are the eggs fertilized you ask? The thought is that females nip at a male’s egg-spots thinking they haven’t picked up all their eggs and while doing so the male releases his sperm (via an opening anterior to the anal fin) which fertilizes the eggs in her mouth.
Aren’t fish great?
Interestingly, the size, shape, colour and number of egg-spots varies among males, species, and whether the water is clear or muddy. Some females prefer males with lots of larger spots, but brightly coloured polka dots may make males stick out like a sore thumb, err, fin to predators. Most recently discovered is that males with fewer egg-spots get beat up more often by other males.
Clearly the story of these curious spots is not yet FINished.
P.S. In other fishes the anal fin is involved with balance while swimming and the spines in the anal fin can be used to age a fish.
Elongate mbuna (Pseudotropheus elongatus), Sam Scālz