WTF? (WHAT’S THAT FISH?) 17: YELLOWHEAD JAWFISH

February 7, 2019 by Rolling Harbour

WTF? (WHAT’S THAT FISH?) 17: YELLOWHEAD JAWFISH

It’s been a little time since I added to the WTF? series, in which some of the more outlandish reef denizens come under close scrutiny. Jawfishes (Opistognathidae) come into this category, not least because of their interesting ways with their eggs. Also, they tend to stick upright out of the substrate, which is not especially fishy behaviour.

More than 50 species of jawfish are found around the world. In the Bahamas, you are most likely to encounter the Yellowhead (or Yellow-headed) variety. And if you think they look slightly… primitive, that’s because they are. In fact, their forebears (forefishes?) originated in prehistoric times, specifically the Miocene era (a lot of million years ago, I didn’t count exactly).

These rather extraordinary little fish superficially resemble certain types of BLENNY. Their modus operandi is to burrow down into sandy, gravelly or other loose substrate. They do so by cramming their mouths with sand and spitting it out to one side. By this means they form a tunnel of sorts in which they can live, and from which they can emerge, or half-emerge and take a look around them. As they do so, they hoover up passing food, mostly plankton and suchlike.

If something looks threatening while they are feeding or having a look around, they can simply duck down into their burrow for safety. They guard their patch against rivals, and behave ‘territorially’ in the jawfish community. One method is to ingest and and then eject sand or gravel at a would-be intruder.

YES, BUT WHERE IS THE REAL ‘WTF?’ FACTOR HERE?

Good question. With a good and original answer. These little creatures are so-called ‘MOUTHBROODERS‘, meaning that they carry their eggs in their mouths. Depending on the species, females, males or even both parents (don’t try this at home) will do this at or after fertilisation. In effect the eggs are safely incubated until they hatch as fry. Then they are on their own.

ARE THERE ANY DRAWBACKS TO THIS UNUSUAL GESTATION METHOD?

Apart from accidentally swallowing the occasional potential junior, the eggs need aeration from time to time. This is achieved by expelling the eggs from the mouth, and quickly sucking them back in again. Try this very short video to see this rather improbable behaviour in action. It’s only 8 seconds blink and you’ll miss the action. The eggs hatch into fry in 8 – 10 days, after which both parents can relax. Until the next time.

Yellowhead Jawfish (Melinda Riger / Grand Bahama Scuba)

Photo Credits: all images from Melinda Riger / Grand Bahama Scuba except (4) Virginia Cooper / GBS; (5) Michael Wolf / Wikimedia; video, Alan Keller. Research: magpie picking, not excluding yet not limited to Wiki…

BAHAMAS REEF FISH (51): BLACK MARGATE

January 28, 2019 by Rolling Harbour

BAHAMAS REEF FISH (51): BLACK MARGATE

The black margate (Anisotremus surinamensis) is a type of GRUNT (see also PORKFISH) found among the reefs and rocks of (mostly) the western Atlantic seaboard, from Florida as far south as Brazil. They are relatively ‘shallow’ fish and they prefer to be close to place where they can live safely and avoid the predators that lurk in open or deep water.

Margates are not usually very large, mostly growing to between 18″ and 30″, although they can grow larger. Thanks to the awesomeness of Wiki and other reliable sources I can confidently report that “…the maximum recorded weight for this species is 5.8 kg (13 lb)“.

MAY WE HAVE THE TRADITIONAL 10 FUN FACTS PLEASE?

Local names include burriquete (Sp) and zapatero or burros (Mex)
There are 10 margate species world wide, including 2 Pacific versions
Their heads slope down to a notably thick lipped mouth in which they have strong teeth
Margates have erectile spines, presumably for defence (I’ve not tested that)
They like to shelter in caves and crevices, on ledges, and in wrecks (see pics)
Margates are ‘solitary fish’ or hang out in small groups
They are night-feeders on a diet of crustaceans, mollusks, smaller fish & urchins
Sadly for them, they are valued by commercial fisheries using baited drift fishing…
…and also targeted by anglers during the spawning season when they shoal (?unfair)
… and also caught as aquarium fish, adding to stock depletion

RELATED SPECIES

PORKFISH

Credits: all photos, Melinda Riger / Grand Bahama Scuba; research from magpie pickings and in particular the interesting mexicanfish.com

SILVERSIDES: BAHAMAS REEF FISH (32)

October 3, 2016 by Rolling Harbour

SILVERSIDES: BAHAMAS REEF FISH (32)

I have no idea if there is a collective noun for a large group of silversides. ‘Frenzy’ would cover it, but that is reminiscent of ‘feeding freezing’ which has a specialist meaning – and anyway, silversides are crazy even when they aren’t feeding. 24/7/12/365 as far as I can make out. I think ‘a panic of silversides’ might be the answer. They are just… all over the place at high speed. Sometimes swirling around pointlessly, other times moving in unison and suddenly all changing direction simultaneously, like a single creature made of tiny shards of silver.

There are quite a few silverside species around the world. The ones in the Bahamas are Atlantic silversides (Menidia menidia), also known in the north east of the United States as ‘spearing’. They seem to exist for two purposes. The main one is to be breakfast, lunch or dinner for larger fish, sea birds and shore birds. The other is for their usefulness in scientific research because of their sensitivity to environmental changes.

In one sense they are easy prey for predators. A determined fish will always manage a snack by swimming into the middle of a panic and (probably) simply by opening its mouth wide. On the other hand, their sheer numbers coupled with the speed and randomness of movement mean that a single may find a degree of safety in numbers. It’s hard for a predator to target any individual fish in the general melee and confusion. Silversides also favour seagrass beds, which give some shelter and protection – and a reasonably safe place to spawn. Or, as some of these photos show, they will hang around wrecks or squeeze into rocky spaces in the reef.

A panic of silversides apparently pouring like a waterfall down through a gap in the reef silversides-waterfall-abaco-kay-politano

WHAT DOES A STATIONARY ATLANTIC SILVERSIDE LOOK LIKE?

meber_u0

Some time ago we used to go to the reef at Fowl Cay Marine Preserve with Kay Politano, and I would snorkel with a small and very basic lo-res underwater camera. I was hampered by being a disgracefully feeble swimmer; by not having snorkelled for a length of time calculable in decades; and by being a complete novice at underwater photography. Despite these not inconsiderable disadvantages I managed to cobble together a few short movies on my computer (I was new to that too). Here’s one that nearly works, in that it gives an idea of what happens if you ‘swim with silversides’. I know you scuba guys all swim with sharks, but cut me some slack here please…

Photo Credits: Main photos Melinda Riger of Grand Bahama Scuba; Silverside Waterfall by Kay Politano; motionless silversides by FISHBASE.ORG. Music: Goldon Giltrap, ‘Fast Approaching’

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

August 8, 2014 by Rolling Harbour

‘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.

HAMLETS (NOT GLOOMY DANES): BAHAMAS REEF FISH (14)

November 28, 2013 by Rolling Harbour

BAHAMAS REEF FISH (14): HAMLETS (NOT GLOOMY DANES)

“Oh, that this too too solid flesh would melt, thaw and…” Ah! Sorry. I’m soliloquising again. Must be Thursday. And the merest mention of Hamlet is enough to set anyone off. But I speak not of noble yet gloomy Danes of Elsinore and of discernibly introspective aspect. These ones are pretty reef fish of the Caribbean seas, mainly in the Bahamas and along the Florida coast. There are a number of different types of hamlet, of which the 4 featured below in Melinda’s amazing underwater images were were encountered in one dive.

SHY (OR GOLDEN) HAMLET

Hamlets have outstandingly interesting reproductive skills, being ‘synchronous hermaphrodites’. They have the unusual benefit of having both male and female sexual organs as adults, permitting imaginative combinations of pairings (though not including self-fertilization). When they find a mate, “the pair takes turns between which one acts as the male and which acts as the female through multiple matings, usually over the course of several nights”. I don’t dare check whether there are websites that cater for this sort of energetic coupling. The wonder is that Hamlets preferentially mate with individuals of their same colour pattern, and that they are not more wanton with their attentions and sexual flexibility.

INDIGO HAMLET

BARRED HAMLET

BUTTER HAMLET

OPTIONAL CULTURAL, HISTORICAL & MUSICAL DIVERSION INSPIRED BY HAMLET

The other notable Hamlet is, of course, the mild cigar equated in the famed commercials with happiness, accompanied by an excerpt from a jazzy version of Bach’s ‘Air on the G String’. Here is one of the best – and possibly the only advert to my knowledge to feature not one, but two excellent Sir Walter Raleigh jokes.

Bach’s well-known descending chord sequence of was of course ~~shamelessly ripped off by~~ ingeniously adapted by Procol Harum for ‘A Whiter Shade of Pale’, their first single in 1967. Relive the Summer of Love right here and now. Is this the music that might even put those versatile hamlets in the mood…

Any fret-tweakers might like to see the sheet music of the Air for guitar – you could even play it on air guitar – which is relatively easy, being in C major.Credits: All fish pics Melinda Riger of Grand Bahama Scuba, except wiki-header; open-source online material; my mp3, dammit – I can’t get the wretched tune out of my mind…

UNDERWATER BAHAMAS: REEF GARDENS (2) – CORALS

August 24, 2013 by Rolling Harbour

UNDERWATER REEF GARDENS IN THE BAHAMAS (2): CORALS

This is part 2 of a series that started out HERE with a selection of anemones, basket stars and Christmas tree worms. The images below show a wide variety of corals. In among them are also sponges and anemones. These photos are evidence of a healthy reef environment in the waters of the northern Bahamas. Abaco’s coral reef is the third largest barrier reef in the world (yes, I hear you – the Great Barrier… And the second is???), providing wonderful and accessible diving / snorkelling opportunities. However, monitoring shows that the incidence of coral bleaching and disease is increasing in the Bahamas, as elsewhere in the world. It’s a sobering thought that your grandchildren may never swim in an environment with any of the living corals shown below…

FORAYS WITH MORAYS (1): EEL APPEAL IN THE BAHAMAS

August 4, 2013 by Rolling Harbour

FORAYS WITH MORAYS (1): EEL APPEAL IN THE BAHAMAS

MORAY EELS are found in most oceans, with around 200 species worldwide. In Bahamian waters, the 3 most common are the green, yellow and spotted morays, all featured below. These ones have been given affectionate names by the divers who encounter them regularly in their home surroundings – Rico, Judy, Wasabi and Earl.

Morays have something of a reputation for aggression, though (like many creatures with teeth) they much prefer to swim away or hide rather than attack. They will defend themselves resolutely, however, so it might be a mistake the get too close.

Hand-feeding morays has become a popular dive activity. However there can be drawbacks. They have poor vision, and may find it difficult to distinguish between food, finger-food and fingers. There are many cases of divers who have lost a finger while hand-feeding moray eels; in some places it has been banned.

The moray eel has strong clamping jaws, and its sharp teeth point backwards

This has two effects. A finger will be held as if by a fish-hook barb; and the eel will not release the grip of its powerful jaws without them being prised apart.

Moray eels have a strong sense of smell, and curious nostrils

Finally, here are two images of a fine spotted moray eel known as ‘Earl’, and a video of a different one

UNDERWATER BAHAMAS: REEF GARDENS & DENIZENS (1)

June 23, 2013 by Rolling Harbour

UNDERWATER REEF GARDENS IN THE BAHAMAS (1)

Animal, vegetable or mineral? If you dive down and take a close look at a reef, you’ll soon find that it isn’t easy to tell what is what… That ‘plant’ is a magic worm; this ‘creature’ is a tentacled plant…

ANEMONES