Ever been swimming along and just get a feeling that something is close by? Sometimes that feeling is justified, especially if you are being followed by a Cornet fish. They appear to follow divers hovering above them. Are they hiding, stalking or playing in bubbles?
You turn round to look at your buddy and suddenly a huge eye is looking at you, attached to a very long snout with a frankly ridiculous looking pouty mouth perched on the end. Jump? Yep, we all did the first time! But what are these guys up to and why do they like divers so much?
There are 4 species of Cornetfish, or Fistulariida to give its Latin family name. Of these 4, we only see one, the Blue Spotted variety. Inhabiting reefs at depth of up to 128m, they are also commonly seen over sandy areas, such as our house reef. They can be seen in groups as well as on their own, although the more adult they are the more likely to be solitary. Babies are ¼ inch long when born, and in the bay it is not unusual to see 10 babies or more, all together, hovering by the reef.
Their long body, equipped with a long whip like tail, is slightly flattened on the top and bottom (so of like a mars bar shape) and they can grow to 148cm although most don’t get much over a metre in length. There unique swimming pattern is due to the fact that the first 4 of their vertebrae are fused together, meaning the head and first part of the body has no movement.
What makes them stand out from many of the other inhabitants of the bay is their ability to change colour, seemingly on a whim. During the day they normally appear with a series of blue spots and lines going the midline of the back from head to tail. At night, they change colouration, now having thick grey and blue bars going across the body. If you are really lucky, and patient, you can see them changing between the two during the day. It is suspected, that this rapid changing during the day is less for camouflage and more for warning. Before you start worrying, if you did stray too close and surprise them, the restricted mouth size would ensure you got more of a suck than a nibble! Hence their choice of food source is quite restricted – they eat small fish, crustaceans and other invertebrates (fish with no bones).
So to answer the original question….hiding, stalking or playing? When you are being followed by one of these critters, you are in fact acting as a large camouflage blanket. How? They follow you, essentially using your body and tank as a shield, and then when they see what they want to eat they dart out from your shadow to ambush their dinner.
Still think they are cute?