Subject: Hump-headed fish: purpose of hump??

From: Jan Forbes <[email-masked]>
Date: Thu, 4 Apr 96 01:46:22 GMT

I am seeking reasons why hump-headed fish such as Maori Wrasse, Lord
Howe Island Doubleheader, Sheepshead Wrasse, and others have humps
on their head.
Reasons suggested by fishy-folk so far include:
1. Sexual display, eg. "my hump is bigger therefore I am a better
'hump' / genetically superior" (Maori Wrase);
2. As a tool (Maori Wrasse to break through coral to get at
molluscan prey, Sheepshead Wrasse to bash the bottom out of sea
urchin prey to extract meat); and
3. As a fluid reservoir which assists navigation / 'homing' (Maori
Wrasse).
Does anyoune have any more examples of such fish and the purpose of
their bumps?
Many thanks, Jan.