REDSPOTTED HAWKFISH: BAHAMAS REEF FISH (35)


Redspotted Hawkfish, Bahamas (Melinda Riger)

REDSPOTTED HAWKFISH: BAHAMAS REEF FISH (35)

The redspotted hawkfish (Amblycirrhitus pinos) is one of a number of species of hawkfishes found worldwide. This one is found on the sub-tropical and tropical reefs of the Western Atlantic, and is therefore a fish you might see when out snorkelling or (more likely) scuba-ing in the Bahamas. These are small creatures – adults are unlikely to exceed 4 inches in length.

Redspotted Hawkfish, Bahamas (Melinda Riger)

There’s not a whole lot else to report about them. They have no medicinal superpowers, for example, nor wickedly toxic spines. A quick scroll through the highways and byways of the interweb reveals that redspotted hawkfish are considered (rightly, I think) to be attractive, tend to be shy, enjoy perching on coral ledges, and are generally benign, except to smaller fishes to which they may show aggression or – worse – an appetite. 

Redspotted Hawkfish, Bahamas (Melinda Riger)

As you might predict, these pretty little fish are popular in the aquarium trade, where on any view they should be kept safe from predators. But maybe captivity is a little limited in opportunities for travel and exploration. They can be bought for (I just checked) $29.99. Or else left alone on a reef to take their chances.

Photo Credits: Melinda Riger / Grand Bahama Scuba, with thanks as per…

JAW-DROPPING: A GROUP OF GROUPER(S)


Grouper at cleaning station - Melinda Riger @ GB Scuba

JAW-DROPPING: A GROUP OF GROUPER(S)

Today is going to be about Jaws – not those sinister-music-sharky types, but a look at the dentition, gill arrangements and oral hygiene of groupers(s). First, though, the vexed question of the correct plural for a group of these fish. I tackled the complex 3-option correct plural of OCTOPUS a while back. Now another problem piscine plural has cropped up.

Tiger Grouper - Melinda Riger @ G B ScubaThe short answer is that the plural is usually ‘groupers’, but also – perhaps less commonly – ‘grouper’ (there’s a similar situation with plural of ‘hare’). One online source suggests ‘grouperer’, but that just seems cumbersome. I think there may be a useful distinction to be made here. When talking about grouper of the same species, one could say “I saw 17 Nassau grouper today”. But where reference is made to mixed species, “I saw plenty of groupers today” implies that there was more than one species – black and tiger, maybe. 

Grouper at cleaning station - Melinda Riger @ GB Scuba

Grouper - Melinda Riger @ G B Scuba

In some of these photos you’ll notice tiny fish attending to the grouper. These are CLEANERS and they are an essential part of the bodily and oral hygiene routine for larger fish species. The big fish call in at so-called CLEANING STATIONS, where the tiddlers remove parasites and dead skin, and polish up the gills. They will even enter the fish’s mouth to pick bits from between its teeth – the deal being that they will not be eaten. This mutually beneficial arrangement is called ‘cleaning symbiosis’ and is carried out by (for example) gobies, wrasses and cleaner shrimps.

Peterson’s cleaner shrimps and cleaner wrasseGrouper with Peterson's cleaner shrimps and wrasse - Melinda Riger @ GB Scuba

Some of these photos show groupers with open gills as well as open mouths, an invitation to the cleaners to do their work. I’d intended to write about how and why gills work but I’ve thought better of it. There’s a lot of detail about chemical exchange involved that, when I looked more closely, seemed rather dull… and therefore outside the remit of this blog, which includes trying to avoid ‘dull’. If you really want to know more, Wiki has a good article HERE. Good luck with that….

Grouper - Melinda Riger @ GB Scuba

Credits: All photos Melinda Riger, Grand Bahama Scuba

ONE GOOD INTERN DESERVES ANOTHER (Part 1)


Coral reef research, Australia (Oscar Ward)

ONE GOOD INTERN DESERVES ANOTHER (Part 1)

Four years ago a young English friend of ours, Oscar Ward, was lucky enough to be offered an internship with the Bahamas Marine Mammal Research Organisation (BMMRO). At the time, he was post-school, and waiting to start a degree course in marine biology at university. He had no practical experience at all, so he had to progress from the menial tasks (scraping barnacles off the bottom of the research boat) to the more adventurous (whale poop-scooping) to the scholarly (collection and analysis of samples and data, including audio file matching of whale calls for identification). The need for hard work, concentration and accuracy were made clear from the outset… and as you will see, Oscar’s short internship has stood him in very good stead during his university course.

Oscar weekending at Gilpin Point – self-sufficientBMMRO Internship - weekend off (Oscar Ward)

From a promising start on Abaco, and with 2 year’s study behind him, Oscar is currently spending the 3rd year of his 4-year course in Australia, working with The Australian Institute of Marine Science. He has been involved in a number of complex projects focussed on corals and reef life – as we all know, a matter of huge concern – and the projections for the future of the reef systems in a time of warming seas and raised acid levels. Oscar also assists PhD students, for example examining the damaging effects of parasitic worms on coral; and the effect of changing light conditions on corals.

Nurse Sharks, Great Barrier Reef (Oscar Ward)

Much of Oscar’s time has been spent doing fieldwork. Often he is at sea, monitoring and collecting samples in the Southern Great Barrier Reef, diving two or three times a day. This work is often carried out in restricted or preservation zones, and with ever-present manta rays, sharks and sea turtles around him.

Manta Ray, Great Barrier Reef (Oscar Ward)

Right now Oscar is involved with the investigations into the recent bleaching events, work that is at the forefront of serious concern for the GBR and far beyond. I have recently corresponded with him – he has definitely not forgotten that his grounding for the fieldwork and studies that he is engaged in – and very likely his career – came from his time on Abaco and the lessons he learned during his time with the BMMRO at Sandy Point.  (In part 2: another good intern, currently at Sandy Point)

Coral reef research, Australia (Oscar Ward)

All photos: Oscar Ward (the header image is taken from a research vessel – no idea how, maybe a drone with fish-eye lens?)

WTF? (WHAT’S THAT FISH?) 13: THE ROUGHHEAD BLENNY


Roughhead Blenny - Melinda Riger / Grand Bahama Scuba

WTF? (WHAT’S THAT FISH?) 13: THE ROUGHHEAD BLENNY

The WTF? series has looked at a number of bizarre reef denizens, and this little fish is certainly that. For a start, its ‘correct’ name is Acanthemblemaria aspera, an excellent challenge for saying 10 times very quickly **. And the name blenny comes from the Greek word for ‘slime’, quite enough to make the poor creature a laughing-stock in the reef community.

Roughhead Blenny - Melinda Riger / Grand Bahama Scuba

There are in fact several hundred blenny species and subspecies around the world. The roughhead is one of the most commonly found in western Atlantic subtropical and tropical waters. These are burrowing creatures, and they find holes in the nooks and crannies of coral reefs – and indeed in the coral itself. Brain coral seems to be a preferred location. Mollusc shells are another. Or they may just bury themselves in the sea floor. 

Roughhead Blenny - Melinda Riger / Grand Bahama Scuba

The  ‘roughness’ of head refers to the whiskery appendages (cirri) on a blenny’s blunt bonce – slender tendril or hair-like filaments. The word cirri is the plural version of the wispy high altitude cirrus clouds that streak the sky. These tendrils are shown clearly in some of the photos here, despite the tiny size of the fish (± 1 inch). 

Roughhead Blenny - Melinda Riger / Grand Bahama Scuba

THESE GUYS LOOK A BIT PRIMITIVE, AM I RIGHT?

To be precise – as far as is possible – blennies can be dated back to the Paleocene Era (or is it an Epoch?). This spanned a period 66 to 56 million years ago – around the time of the formation of the Rolling Stones.

Roughhead Blenny - Melinda Riger / Grand Bahama Scuba

You can find out more about roughheads in this excellent eHow video I came across after I’d written this post, to which I should now add that there is considerable colour variation in this subspecies, as you may already have noticed…

** You can also try this with ‘Red Lorry Yellow Lorry’. Yes I know. Maddening, isn’t it. You can’t stop now you’ve started. Sorry…

Credits: all photo, Melinda Riger; video, eHow

PREHENSILE TALES FROM THE REEF (3): SEAHORSING AROUND


Seahorse (Adam Rees / .Scuba Works)

PREHENSILE TALES FROM THE REEF (3): SEAHORSING AROUND

It’s Friday at last. It’s springtime. A spirit of benign goodwill is evident in the vicinity of Rolling Harbour. Seahorses are irresistible. Don’t even try to pretend they don’t make you smile. Hippocampophobia is an affliction that, as yet, has never been diagnosed in a human being – for whom fear of beards, clowns and the number 5 (quintaphobia) are known medical conditions. Immerse yourself with these little creatures – and then have a good weekend.

Seahorse (Adam Rees / Scuba Works)Seahorse (Adam Rees / Scuba Works)Seahorse (Adam Rees / Scuba Works)Seahorse (Adam Rees / Scuba Works)Seahorse (Adam Rees / Scuba Works)Seahorse (Adam Rees / Scuba Works)

All fantastic hippocampi photos: Adam Rees / Scuba Works

DUSKY DAMSELFISH: BAHAMAS REEF FISH (34)


Dusky Damselfish, Bahamas (Melinda Riger)

DUSKY DAMSELFISH: BAHAMAS REEF FISH (34)

The dusky damselfish Stegastes fuscus is one of a number of damselfish species found in Bahamian waters. These small reef fish, in adult form, are dark coloured as their name suggests. Their appearance is brightened by having distinctive blue edges to their fins.

Dusky Damselfish, Bahamas (Melinda Riger)

These fish feed mainly on algae, with a preference for red. They top up their diet with small invertebrates. Their value to the reef is that their feeding patterns help to prevent coarser seaweeds from becoming dominant in areas where these are prevalent. 

Dusky Damselfish, Bahamas (Melinda Riger)

Like many damselfish, the dusky is a territorial species, guarding its chosen area of seabed and the food sources within it by repelling intruders – often seeing off far larger algae-grazing fishes such as parrotfish and wrasse. Yet besides their aggressive traits, they are also rather cute, as photo #2 shows!

Dusky damselfish, Bahamas (Melinda Riger)

All photos: Melinda Riger / Grand Bahama Scuba

BLUEHEAD WRASSE: PRIVATE LIFE LAID BARE


bluehead_wrasse_thallasoma_bifasciatum_oregonstate-edu-pinterest

BLUEHEAD WRASSE: PRIVATE LIFE LAID BARE

The bluehead wrasse (or blue-headed wrasse) Thalassoma bifasciatum is a denizen of the coral reefs of the tropical waters of the western Atlantic Ocean. This bright little 4-inch fish is… a wrasse with a blue head. No more and no less. Unless it’s a juvenile. Then it is mainly bright yellow. It’s similar to BLUE TANG (aka ‘the Disney Dory’), which starts life bright yellow and grows up to be blue.

blue-head-wrasse-melinda-riger-g-b-scuba-copy

The species may be found singly, in pairs or small groups, or in schools.  They have an important role to play in the life of the reef. They are CLEANER FISH, vital to the health and wellbeing of the larger species they attend to, and thus of the reef itself. This is ‘cleaning symbiosis’, a relationship of mutual benefit. The big fish get cleaned; the little fish have a useful function and – importantly for them – therefore don’t get eaten. 

thalassoma_bifasciatum_bluehead_wrasse_san_salvador_island_bahamas-james-st-john-wiki

Having said that, blueheads are of course fair game as a snack for species that aren’t in the market for their cleaning services. And, unfairly, some species that are content to let cleaner gobies runtle around their gills and mouths are not so considerate of the wrasse. Some types of grouper and moray eel, for example.

bluehead_wrasse

TELL US EXACTLY SEVEN BLUEHEAD WRASSE FACTS

  • Juveniles can alter the intensity of their colour, stripes & bars
  • The bluehead wrasse is a ‘protogynous sequential hermaphrodite’
  • All are born female**. Some change sex to male during maturation (see below)
  • Food includes zooplankton, small molluscs and small crustaceans…
  • …and parasites / other juicy bits (fungal growths, anyone?) from bigger fish
  • The main threat to the species is coral reef degradation or destruction
  • The bright colours invite aquarium use, but the trade is not a significant one

** Some sources suggest some are born male and remain male. I’m not sure which is right

A juvenile bluehead (with feather-duster worms) – mostly yellow, with a pale underside
Bluehead Wrasse juvenile (wiki)

THE REMARKABLE SEX LIFE OF THE BLUEHEAD WRASSE

This is an unavoidable topic, I’m afraid. The bluehead’s sex life is the most interesting thing about them, and this is no time to be prudish. It is the subject of extensive scientific research, not all of which I have read since I decided to write about the species last night. Like many human relationships, “it’s complicated”, but in a conch shell it boils down to this:

  • To recap, BWs are born female and as they mature, some become male.
  • Males reach an ‘initial phase’ when they can breed in groups with females
  • Some males grow even larger & reach full colouration. This is the ‘terminal phase’
  • These large males aggressively chase away smaller ones & seek females to pair with
  • Their state of readiness (as it were) is signalled by colour changes
  • This behaviour is similar to that seen in many city centres in a Saturday night
  • The smaller fish have one bonus – their sperm count is higher than a dominant male
  • Prozac tests have shown that the drug reduces a dominant male’s aggression

blue-headed_wrasse_det (wiki)

As the excellent organisation OCEANA puts it: Bluehead Wrasses may reproduce in four different ways throughout their lifetime:  1) as a female in a group spawning event; 2) as a female in a pair spawning event within the territory of a large male; 3) as a small male in a group spawning event; and 4) as a dominant, terminal male in a pair spawning event within its own territory.

A cropped still from a video I took at Fowl Cay marine reserve. I’ve looked at dozens of images online and not found one that was all blue with a yellow end to its tail fin. Maybe it’s not a BW at all. Or it’s a different type of fish completely. Or perhaps it is just an all-blue alpha male.bluehead-wrasse-fowl-cay-mr-abaco

Credits & Sources: Melinda Riger; Adam Rees; James St John; Oregon State edu / Pinterest; Wiki images; self; Oceana; IUCN; magpie pickings

A bluehead wrasse passes the time of day with a gruntbluehead-wrasse-grunt-adam-rees