CONJOINED COMMENSURATES

This post is by special request from Olivia.
This is a great example of natural symbiosis. The shrimp, an Alpheid, nearly blind, lives in a burrow it digs in the substrate along with an Orange Spotted Shrimp goby. Amblyeleotris guttata (Fowler, 1938)
Normally a shrimp would move around with it`s antennae, pointed forward. As you can see, one antennae, is folded back over the shrimp & is touching the Goby. It will never go any farther away than the length of it`s antennae from the Goby.
If danger approaches, the shrimp gets a signal from the Goby through it`s antennae, & scoots down into it`s burrow. The fish then immediately follows.
The shrimp thus is protected by the seeing fish, & in return the fish eats the small "bugs" the shrimp disturbs while burrowing.
These shots are hard to take because of the everpresent early warning system the pair uses. If the shrimp is out when I approach , the Goby will alert it as if I represent danger. This degree of difficulty is compounded by the fact that the burrows, interconnected below the surface, are very close to the tank wall. If they lived further back it might be a little easier because I would not be seen as a danger so readily.
The danger also comes from within the reef itself. By clicking on Planet Earth, you will see a Coral Banded Shrimp on the prowl in close proximity to the burrow, being stood up to by the Goby.
In the header image is where Waldo can be found. Clicking Waldo will take you to Waldo`s world. This crab, unknown Genus, is a little smaller than a dime & often just seem to appear out of nowhere but may have been in the reef for years. It`s always a new thrill when you find a new animal in your tank. These creatures, called "Hitch-hikers", come into the reef in early stages of their developement on live rock, the solid foundation upon which a reef builds. I call him Waldo, because I always wonder, Where`s Waldo.