Sunday, 30 October 2016

Pilot fish and Longtoms

Pilot fish famously follow sharks around, however it seems that this relationship is repeated on a smaller scale. I observed a longtom (also known as a needlefish) about 40 cm long hunting in the surface waters beside the Cairns waterfront boardwalk.  Then I saw that the longtom was not alone, it had a group of tiny fish following its every move.  Longtom are predators on other fish so following a longtom would seem to be risky for a little fish.   Additionally the longtom would zip a few metres forward to chase prey which I did not see and must have left the little fish behind.  Moments later, the little fish would be escorting the longtom again. 

Close-up of the fish escorting the longtom (click to enlarge)
The longtom appears to belong to the genus Tylosurus and I am not sure what the smaller fish are, possibly something in the tuna/trevally family.  Larger longtom occasionally spear people including sea kayakers as the sprint across the surface bouncing every six metres or so.  They tailwalk to pick up speed and will travel 20 m with only the tip of their tail in the water, the rest of their body in the air and leaning forwards at quite an angle.  Longtoms also apparently lack stomachs, something which I just found out. 
Longtom have a long beak filled with sharp teeth for catching little fish

The little fish would even swim on top of the longtom's head!