280 UNDERWATER GUIDE TO MARINE LIFE 



almost jerky in contrast to the blenny's quick, but more flowing, wavelike 

 motions. Gobies cannot walk on their ventral fins as blennies can. 



This is as confused a group regarding its names as one is liable to meet. There 

 are hordes of species found in tropical and temperate zones the world over, both 

 in salt and fresh waters. Furthermore, males and females not only difi^er from 

 each other in colorations, but also change their colors widely in response to 

 emotional as well as environmental stimuli. In spite of these difficulties, these 

 are among the most rewarding of fishes to study. They are small, unafraid, 

 common in shallow water, can be approached closely, and have remarkable 

 courtship and breeding behavior. In all these respects they parallel blennies 

 ecologically. Several of them show a marked tendency to become semiterrestrial. 

 They can trap water in their gill chambers by means of a membrane and thus 

 they can live for several hours out of water. Fishermen are able to keep some 

 species alive for a week stored in damp seaweed. 



Gobies "home" to a particular spot and have good memories for their home 

 territory. 



If the swimmer remains stationary in the presence of gobies, they will soon 

 grow accustomed to him and may even use parts of his body as vantage points. 



Gobies have elaborate courtships. The male selects a hole in the reef or rocks 

 or a shell or even builds a house of mud and sand. Then he entices a female to 

 his lair by means of peacocklike displays of fins and movements. The female lays 

 eggs and departs. The male may then fickly entice one or more additional 

 females to lay eggs in the same fashion. Then the male guards his precious 

 horde, being extremely intolerant of intruders and not eating until the eggs are 

 hatched. 



These pert, lively, somewhat irascible little fishes are rarely over 6 inches in 

 length. One of them matures at half an inch. The largest reaches 2 feet. Most 

 are able to survive in very stagnant water. They are fiercely carnivorous on small 

 invertebrates and range throughout tropical and warm temperate seas. 



GOBIES: Family Gobiidae 



MAPO (sheep's head MOLLY miller) : Bathygohtus sof orator— Color Plate 3 



Size: Up to 6 inches. Mostly much smaller. 



Distrihtition: West Indies north to Cape Hatteras. Western coast of Mexico. 



Identification: The five pectoral rays on the dorsal side of the pectoral fin 

 separate this fish from all other gobies. The color is variable but is usually pale 

 gray to green or brown with mottlings or vertical bars. When over light bottoms 

 or when alarmed, the fish assumes a very light phase. 



Habits: This fish is very common in shallow waters and tidepools throughout 

 its range. It is a typical goby in size, shape, and habits. This is the species that 

 has been the most studied of the gobies. Aronson (1951) made a fascinating study 

 of its homing and leaping behavior. He noticed that mapos frequently leap un- 

 erringly from tidepool to tidepool, even though they could not possibly see where 

 they were going to land due to the steep sides of the tidepool from which they 

 leapt. The leap is accomplished by an extremely rapid straightening of the tail. 

 Aronson says that this accurate jumping does not result from trial and error 

 learning, but "it is suggested that these gobies swim over the tidepools at high 



