INTERNATIONAL SHARK WEEK? IT’S SO OVER… EXCEPT HERE


Sharks in Bahamas - Melinda Riger / Grand Bahama Scuba

INTERNATIONAL SHARK WEEK? IT’S SO OVER… EXCEPT HERE

There’s never a day without a ‘Day’, nor a week without a ‘Week’. Almost all creatures under the sun are celebrated in some regular calendar-based time-frame. With the exception of No-see-ums: I’ve checked – there is no national or international Ceratopogonidae Day in any online calendar. 

Sharks in Bahamas - Melinda Riger / Grand Bahama Scuba

By a mere 2 days, I have missed Shark Week, a happening tied in with the Discovery Channel, and heralded by an amusing trailer that features no actual sharks… So, belatedly, here are some cool shark photos to enjoy, in case you didn’t get enough of them last week, or (like me) had other fish to fry.

Sharks in Bahamas - Melinda Riger / Grand Bahama Scuba“I’m so glad we agreed to watch each other’s backs…”

Sharks in Bahamas - Melinda Riger / Grand Bahama Scuba

 Meet Nurse Betty, as she is known to diversSharks in Bahamas - Melinda Riger / Grand Bahama Scuba

MANGROVES: THE SHARK NURSERY

As all children are taught and some adults know, the mangroves that grow in the shallow waters around the islands of the Bahamas are of enormous ecological significance. This isn’t the place to expand on that now, but it is worth mentioning that the mangrove swamps are the nurseries of young sharks (‘pups’) until, as juveniles, they are old enough to leave the safely of their home for deeper waters. Check out the short video below.

Sharks in Bimini Bahamas - biminis-marine-protected-areaSharks in Bimini Bahamas - biminis-marine-protected-area

Spot the REMORA hitching a ride on this shark’s backSharks in Bahamas - Melinda Riger / Grand Bahama Scuba

Nurse shark – note the twin barbels (cf recent Goatfish article)Sharks in Bahamas - Melinda Riger / Grand Bahama Scuba

Sharks in Bahamas - Melinda Riger / Grand Bahama Scuba

HAMMERHEADS FROM BIMINI Sharks in Bimini Bahamas - Grant Johnson / 60 Pound Bullet   Sharks in Bimini Bahamas - Grant Johnson / 60 Pound Bullet

These wonderful photos were all taken in Bahamian waters. Melinda Riger of Grand Bahama Scuba is, as ever, the star snap-getter of sharks (and indeed all other marine creatures). Special thanks are also due to Grant Johnson / 60poundbullet and Neal Watson / Bimini Scuba Center for occasional use permission of photos – especially of hammerheads – that are, well, eye-popping. Video from ‘ZeroEye’

Sharks in Bimini Bahamas - Grant Johnson / 60 Pound Bullet

BAHAMAS REEF FISH (53): YELLOW GOATFISH


Goatfish, Bahamas (Melinda Riger / G B Scuba)

BAHAMAS REEF FISH (53): YELLOW GOATFISH

GOATFISHES belong to the mullet family, a large group of species with a flexible membership. In other words, there is disagreement as to whether certain fish are mullet or not. For present purposes, it’s not our problem – no one doubts that the goatfish is a mullet.

Goatfish, Bahamas (Melinda Riger / G B Scuba)

SO WHY ARE THESE CALLED GOATFISH? WAS SOMEONE KIDDING?

These fish get their name for the pair of so-called ‘barbels’ below their mouths (see image below), thought to be reminiscent of a goatee beard. The name has Latin origin, ‘barbula‘, meaning a small beard. Linnaeus may have had a hand in this choice of description.

Goatfish, Bahamas (Melinda Riger / G B Scuba)

WHAT IS THE FUNCTION OF THE BARBELS?

The barbels are sensory organs which, depending on the creature, may be located on either side of the mouth, on the chin, or even extending from the nostrils. In broad terms, the barbels are where the taste buds are located. They help a fish to find food even when the water is stirred up or murky or at night, and are used to probe into sand or into holes in the reef for prey.  

Goatfish, Bahamas (Melinda Riger / G B Scuba)

WHY ARE THEY OFTEN SEEN WITH YELLOWTAIL SNAPPERS, GRUNTS & PORKFISH?

Goatfish have limited means of self-protection. They are not poisonous or venomous, they have no spines or razor-sharp teeth, nor ink to squirt. They do have an ability to change colour rapidly to blend into their surroundings – e.g. over pale sand – to make them less conspicuous to predators. Overall, however, they are docile and probably delicious to many other species. Their bright hues may have some function as aposematic colouring to warn, scare or repel potential predators, but this is possibly of limited use among the familiar reef denizens. So instead the goatfish goes in for so-called protective mimicry, as shown in the image above.

Goatfish, Bahamas (Melinda Riger / G B Scuba)

PROTECTIVE MIMICRY?

Goatfish and yellowtail snappers (in particular) are similar in size, appearance, coloration and behaviours, though the feeding patterns differ. The reason they are often found in mixed groups on the reef is for the individual protection they gain in a larger mixed school. This really amounts to taking advantage of safety in numbers (especially for the fishes in the middle). Here’s a very recent photo that shows exactly this scenario – a large mixed shoal of two almost indistinguishable fish species.

Goatfish & Yellowtail Snappers shoaling (Melinda Riger, GB Scuba)

IS THIS A ‘SPOT THE DIFFERENCE’ TEST?

If you’d like to make it so! (click on the image to enlarge it). Look out for the fish with the barbels (Goatfish); and the fish with the larger, more deeply forked tails (Snappers). A predator won’t take a great deal of notice of the finer points of difference of course, but overall this large mixed shoal gives a degree of protection to individual fish in the unit as a whole

Goatfish, Bahamas (Melinda Riger / G B Scuba)

ARE GOATFISH EDIBLE?

Goatfish are eaten in many ares of the world, though I can’t recall seeing it on a Bahamian menu. The Romans ate the local mullet / goatfish species, but then they ate many things that we do not now consider as permissible food – dormice in honey for example. Rather revoltingly, the goatfish were served live so that guests could watch them die and see the amazing change of colours in the process. Barbaric? But don’t we cook live… well, never mind that.

Goatfish, Bahamas (Melinda Riger / G B Scuba)

Photos: all great photos from Melinda Riger / Grand Bahama Scuba; magpie research pickings inc. the abstract of a scientific paper with about 23 authors; tip ‘o the hat to Wiki, no seriously

Goatfish, Bahamas (Melinda Riger / G B Scuba)

MEET ARNOLD: BE A BAHAMAS BLACK GROUPER GROUPIE


Black Grouper, Bahamas (Arnold) - Melinda Riger @ GB Scuba

MEET ARNOLD: BE A BAHAMAS BLACK GROUPER GROUPIE

The Black Grouper, like all its cousins, has the twin disadvantages of being fished for sport and fished for food. As demand for grouper on the menu rises, so does its vulnerability. The species is described as a ‘slow breeder’, so a depleting population has less chance of sustaining numbers. The consequence is an exponentially diminishing stock of the species. The equation is simple: fewer fish means less and less stock replenishment.

Black Grouper, Bahamas (Arnold) - Melinda Riger @ GB Scuba

Formerly plentiful, these groupers (like other grouper species) have moved from an IUCN listing of ‘Least Concern’ to ‘Near-Threatened’. Whatever effect climate change may be having on the oceans, stock depletion of this noble species also has more direct human causes.

Black Grouper, Bahamas (Arnold) - Melinda Riger @ GB Scuba

An adult black grouper’s diet consists of small fish and squid. Juveniles feed primarily on crustaceans. However, certain tiny reef fish – blennies and gobies for example – are important to the species as ‘cleaners’. You can read about their significance by clicking CLEANING STATIONS.

Black Grouper, Bahamas (Arnold) - Melinda Riger @ GB Scuba

The service performed by tiny fish on large ones (not only groupers) is an example of a symbiotic relationship known as ‘mutualism’**, in which both parties benefit (the little fishes get gacky bits of grouper to eat). The cleaners are able to do their work inside the gills and even the mouth of the host without being at risk.

Black Grouper, Bahamas (Arnold) - Melinda Riger @ GB Scuba

The NASSAU GROUPER has a defined and enforced closed season to help maintain numbers. It will be interesting to see if the same protection is eventually extended to the black grouper and indeed to other grouper species.

** The other two types of symbiotic relationship are commensalism, in which only one species benefits while the other is neither helped nor harmed; and parasitism, where one creature (the parasite) gains, while the other (the host) suffers.

RELATED POSTS

TIGER GROUPER

NASSAU GROUPER

RED HIND

GRAYSBY

Credits: all photos Melinda Riger of Grand Bahama Scuba 

Black Grouper, Bahamas (Arnold) - Melinda Riger @ GB Scuba

BAHAMAS TURTLES: BE AWARE BUT DON’T BEWARE


Green Turtle Eye (Melinda Riger / Grand Bahama Scuba)

GREEN TURTLE WATCHING

BAHAMAS TURTLES: BE AWARE BUT DON’T BEWARE

MAY 23 is another one of those ‘species awareness’ days. Somewhere in the world, it seems that every day of the year has a creature to be aware of. As the Sixth Extinction looms (the one we’ve promoted in basically two generations), a state of heightened awareness is where we should all be at. 

TURTLES BY ADAM REES / SCUBA WORKS

Hawksbill Turtle (Adam Rees / Scuba Works)

Hawksbill Turtle (Adam Rees / Scuba Works)Hawksbill Turtle (Adam Rees / Scuba Works)

That’s not an end in itself of course – it’s merely the first step to doing something about the species in question… and beyond that, every species. We’ve screwed up their world for them. Awareness is just a wake-up call to action. Support a cause. Join an organisation or group. Support campaigns. Sign up. Write stuff. Do stuff. Don’t do other stuff. Even wearing a “Save the Great-crested Newt” T-shirt would be better than nothing.

TURTLES BY MELINDA RIGER / GRAND BAHAMA SCUBA

Hawksbill Turtle (Virginia Cooper / Grand Bahama Scuba) Hawksbill Turtle (Melinda Riger / Grand Bahama Scuba)Hawksbill Turtle (Melinda Riger / Grand Bahama Scuba)

Back to the turtles. I have featured a few great sea turtle photos (none of them mine) to concentrate the mind on today’s special species – one of the most loved and admired of the sea creatures of the Bahamas archipelago. If they go, we humans may not be far behind (but at least we won’t have stomachs full of plastic trash).

TURTLES: HAPPY TOGETHER!

Credits: Melinda Riger, Adam Rees, Virginia Cooper – and to all for their work in revealing the wonderful world beneath the ocean waves

Hawksbill Turtle (Melinda Riger / Grand Bahama Scuba)

 

TUNICATES: SESSILE ASEXUAL SEA-SQUIRTS


Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

TUNICATES: SESSILE ASEXUAL SEA-SQUIRTS

Painted Tunicates Clavina picta are one of several species of tunicate ‘sea-squirts’ found in Bahamas and Caribbean waters. These creatures with their translucent bodies are usually found clustered together, sometimes in very large groups. One reason for this is that they are ‘sessile’, unable to move from where they have taken root on the coral.

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

HOW DO THEY FEED?

Like most if not all sea squirts, tunicates are filter feeders. Their structure is simple, and enables them to draw water into their body cavity. In fact they have 2 openings, an ‘oral siphon’ to suck in water; and an exit called the ‘atrial siphon’. Tiny particles of food (e.g. plankton) are separated internally from the water by means of a tiny organ (‘branchial basket’) like a sieve. The water is then expelled. 

Diagram of adult solitary tunicate

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

WHAT DOES ‘TUNICATE’ MEAN?

The creatures have a flexible protective covering referred to as a ‘tunic’. ‘Coveringates’ didn’t really work as a name, so the tunic aspect became the name. 

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

IF THEY CAN’T MOVE, HOW DO THEY… (erm…) REPRODUCE?

Tunicates are broadly speaking asexual. Once a colony has become attached to corals or sponges, they are able to ‘bud’, ie to produce clones to join the colony. These are like tiny tadpoles and their first task is to settle and attach themselves to something suitable – for life – using a sticky secretion. Apparently they do this head first, then in effect turn themselves upside down as they develop the internal bits and pieces they need for adult life. The colony grows because (*speculation alert*) the most obvious place for the ‘tadpoles’ to take root is presumably in the immediate area they were formed.

 

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

APART FROM BEING STATIONARY & ASEXUAL, ANY OTHER ATTRIBUTES?

Some types of tunicate contain particular chemicals that are related to those used to combat some forms of cancer and a number of viruses. So they have a potential use in medical treatments, in particular in helping to repair tissue damage.

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

Credits: all fabulous close-up shots by Melinda Riger / Grand Bahama Scuba; diagram from depts.washington.edu; magpie pickings with a particular mention of an article by Sara MacSorley

Painted Tunicates Bahamas (Melinda Riger / GB Scuba)

 

‘REEF ENCOUNTER’ 1: GRAY ANGELFISH


Gray Angelfish 9with four-eyed butterflyfish), Bahamas (Melinda Riger / Grand Bahama Scuba)

‘REEF ENCOUNTER’ 1: GRAY ANGELFISH

Today I learn from a cheery message from WordPress that my illustrated ramblings have been going on for exactly X years, where X is greater than 5 but less than 10. Time to start a new theme: channelling my inner Noel Coward, I am introducing a new mainly pictorial series provisionally called ‘Reef Encounter’. All the awesome beauty of reef life will be here.

Gray Angelfish, Bahamas (Melinda Riger / Grand Bahama Scuba)

In the past I have posted about GRAY ANGELFISH, one of three kinds of angelfish found in the northern Bahamas. Today, I am featuring some more recent images of these pretty creatures. Note in particular the striking shape and colour of their mouths, the blue being found also on the fin edges at the back.

Gray Angelfish, Bahamas (Melinda Riger / Grand Bahama Scuba)Gray Angelfish, Bahamas (Melinda Riger / Grand Bahama Scuba)

On this otherwise gray fish, you’ll also find touches of yellow on the face and the edges of the front fins. In the header image there’s another little fish in the bottom right corner. Not a baby angelfish, but a FOUR-EYED BUTTERFLYFISH – a species that will feature in own right in due course

Gray Angelfish, Bahamas (Melinda Riger / Grand Bahama Scuba)

All fabulous photos by Melinda Riger / Grand Bahama Scuba

Gray Angelfish, Bahamas (Melinda Riger / Grand Bahama Scuba)

BAHAMAS REEF FISH (51): BLACK MARGATE


Black Margate (Melinda Riger / Grand Bahama Scuba)

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.

Black Margate (Melinda Riger / Grand Bahama Scuba)

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)“.

Black Margate (Melinda Riger / Grand Bahama Scuba)

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

Black Margate (Melinda Riger / Grand Bahama Scuba)

RELATED SPECIES

PORKFISH

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

Black Margate (Melinda Riger / Grand Bahama Scuba)