JACKKNIFE FISH: BAHAMAS REEF FISH (30)


Jackknife Fish ©Melinda Riger @ GB Scuba

JACKKNIFE FISH: BAHAMAS REEF FISH 30

The rather uncomfortably ‘double-k’  Jackknife fish is one of 3 types of similar drumfish subspecies of Equetus found in Bahamas waters. The others are the High Hat and the SPOTTED DRUMFISH – the first fish featured in this series. Each of these drumfish species has juveniles that are elegant and delicate, becoming more conventionally fishlike as they grow to adulthood, as the final image shows.

Jackknife fish (juv) ©Melinda Riger @ G B Scuba copy

I always want to stick a hyphen in to separate each k: jack-knife fish. I think it’s an English thing. I have seen, at the other extreme, ‘jack-knifefish’, which looks most weird of all. Checking online, jackknife fish wins by a distance as the correct spelling. 

Jackknife Fish (juv) ©Melinda Riger @GB Scuba

These little fish, typically between 6 and 9 inches, inhabit the coral reefs of the Caribbean, the Gulf of Mexico, Florida and the Bahamas. Juveniles eat plankton and similar organism, graduating to small crabs and shrimps as adults.

Jackknife Fish ©Melinda Riger @ G B Scuba

A FULLY GROWN JACKKNIFE FISH (NOAA)Jackknife fish adult_NOAA_Photo_Library

Like other drumfishes, the jackknife can produce ‘croaking’ or ‘drumming sounds. This involves the fish beating its abdominal muscles against its swim bladder. There’s a lot more to it than my rather simplistic summary, but it’s probably as much as anyone needs or wants to know… The primary reason is believed to relate to mating. Other reasons include ‘low-level aggression’, and keeping in touch with each other in turbid waters.  I prefer the unscientific theory that sheer happiness makes them croak. Here’s a short video of a happy juvenile Jack knife fish (that’s yet another spelling variant…)

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Credits: Melinda Riger / GrandBahama Scuba; NOAA

‘ELEGANTLY WEIRD’ – SPOTTED DRUMFISH JUVENILES: BAHAMAS REEF FISH (20)


‘ELEGANTLY WEIRD’ – SPOTTED DRUMFISH JUVENILES: BAHAMAS REEF FISH 20

I’ve posted before about the rather extraordinary SPOTTED DRUMFISH, one of those reef fish which in juvenile form is very different from the adult. This species was first up in the Bahamas Reef Fish series – click above link. Here are a few recent images, courtesy of Melinda Riger. The first three show the juvenile form (note the piscine photobomb in the first one). The last shows a group of adults hanging out on the reef with (I think) some soldierfish. You can see how the juvenile drumfish becomes the adult, but those little stripy bullet-heads with their two long elegantly trailing appendages differ considerably from the rather solid-looking spotty / stripy adults with their dramatic punko-rockabilly quiffs.

Drumfish (juv) 3 ©Melinda Riger @ Grand Bahama Scuba Drumfish (juv) 4 ©Melinda Riger @ Grand Bahama ScubaDrumfish (juv) 2 ©Melinda Riger @ Grand Bahama Scuba Drumfish ©Melinda Riger @ Grand Bahama Scuba