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)

BLACK DURGON: A TRIGGERFISH OF DISTINCTION


Black Durgon Triggerfish (Melinda Riger / Grand Bahama Scuba)

BLACK DURGON: A TRIGGERFISH OF DISTINCTION

The Black Durgon (Black Triggerfish) seems to be a fairly rare triggerfish in Bahamas waters. I say that not because I know, but because there is very little mention of them in a Bahamas context. In fact, the (not especially profound) research I have done suggests it is not (originally?) really native to the Bahamas region at all. Correction of this impression welcome!

Black Durgon Triggerfish (Melinda Riger / Grand Bahama Scuba)

These fish have the ability to change colour, according to their surroundings. Mostly, they seem completely black. However they have intricate blue markings to the head, and regular patterning on their flanks that resembles the sort of thing one idly doodles during a long and less then attention-holding phone call (or the ‘hold music’) – see Header Image. They also have dramatic pale stripes where their fins join the body.

Black Durgon Triggerfish (Getty Images)

These fish have a varied diet that includes small fish, squid and shrimps, with side-helpings of algae, zooplankton and marine plants. And…

FUN FACT (REALLY!)

The Black Durgon has been studied, of course. One piece of research discovered that they… erm… ingested the feces and vomit of a species of dolphin. Other reef fish in the area did so too, but the Black Durgon was much the keenest on this distinctive  diet. So these are ‘offal-eating’ fish… and welcome to it. Here’s a short video to take your mind off it all…

I’d be interested to hear from anyone who has encountered these fish in Abaco waters. I ought to look further into their prevalence. Maybe they just don’t get much publicity. They need a new agent.

Black Durgon Triggerfish (Melinda Riger / Grand Bahama Scuba)Credits: Photos by Melinda Riger / Grand Bahama Scuba except #3, Getty Images; Kwik-Viddy, Cassandra-Tel; inadequate research, Author

BAHAMAS SEA TURTLES: IN THEIR ELEMENT


Green Turtle, Bahamas (Melinda Riger / Grand Bahama Scuba)

Green Turtle

BAHAMAS SEA TURTLES: IN THEIR ELEMENT

Of all the sea creatures in the limpid waters of the Bahamas, turtles are rightly among the most loved. These days, what with habitat degradation below the waves and the destruction of nesting sites on land, turtles have a hard time simply fighting for survival. And that’s before they have ingested the plastic garbage that mankind pours into their living quarters, by now probably beyond effective remedial action forever. So here are some gorgeous turtles to admire, while stocks last…

Hawksbill Turtles enjoying life around a still-healthy reefHawksbill Turtle, Bahamas (Melinda Riger / Grand Bahama Scuba) Hawksbill Turtle, Bahamas (Melinda Riger / Grand Bahama Scuba)

A hawksbill snacking on a spongeHawksbill Turtle, Bahamas (Melinda Riger / Grand Bahama Scuba)

Interaction with other underwater species: gray angelfish and a rock beautyHawksbill Turtle, Bahamas (Melinda Riger / Grand Bahama Scuba) Hawksbill Turtle, Bahamas (Melinda Riger / Grand Bahama Scuba)

If you are concerned about the plight of turtles and indeed other denizens of the thickening plastic soup we still call ‘ocean’, you could investigate the work some of the organisations that tackle the problem in the Bahamas and beyond. To name but a few, our own FRIENDS OF THE ENVIRONMENT; the BAHAMAS NATIONAL TRUST; the Bahamas Reef Environmental, Educational Foundation BREEF; the CAPE ELEUTHERA FOUNDATION; and the SEA TURTLE CONSERVANCY

Photo credits: all great photos by Melinda Riger / Grand Bahama Scuba

WTF? (WHAT’S THAT FISH?) 15: SCORPIONFISH


Caribbean Scorpionfish, Bahamas (Melinda Riger / G B Scuba)

WTF? (WHAT’S THAT FISH?) 15: SCORPIONFISH

The WTF? series is aimed at shedding light on fishes that are unusual. Or very unusual. Or puzzling, dangerous and maybe less than elegant in appearance. The scorpionfish is one such. It belongs to a large family, the Scorpaenidae, and many types are found throughout the world, especially in the Pacific and Indian oceans. LIONFISH, the newcomers to the western Atlantic, are a species of scorpionfish. 

Just another rock on the seabed…Caribbean Scorpionfish, Bahamas (Melinda Riger / G B Scuba)

WHY ‘SCORPIONFISH’? THEY LOOK SCARY. ARE THEY DANGEROUS?

One feature common to many scorpionfish species is that they are highly venomous. As the name suggests, a sting is involved. Or several stings. These come from the creature’s sharp spines, which are coated with mucus, and are to be avoided. If you want to pet one, the dorsal, anal and pelvic fins are the ones to steer clear of – these all have venom glands at the base. The spines act like injection needles. Scorpionfish aren’t naturally aggressive (except to prey), but they know how to defend themselves if need be. If you get ‘got’, you are in for “extreme pain and burning sensation”.

Caribbean Scorpionfish, Bahamas (Melinda Riger / G B Scuba)

DO THEY HAVE ANY OTHER TRICKS TO WATCH OUT FOR?

As many have written, scorpionfish are ‘Masters of Camouflage’. They are able to disguise themselves very effectively. Their appearance is a remarkably adapted to their surroundings, as if covered in a raggle-taggle of colourful algae. They can change colour to aid concealment. They can flick sand over themselves as they settle on the seabed. These ploys enable them to lie motionless on a coral reef or on the seabed, ready to ambush their prey. This consists mainly of small fishes and crustaceans, but really anything edible that will fit in their mouths is fair game. 

Concealed against coralCaribbean Scorpionfish, Bahamas (Melinda Riger / G B Scuba)

HOW DO THEY FEED?

The large mouth of scorpionfishes has a particular function. They don’t have teeth because they have no need. A scorpionfish can open its mouth and its gills simultaneously, thereby creating an instant vacuum that will suck in its prey in a flash. I have seen this described as “a nearly imperceptible split-second movement (15 milliseconds)”

Caribbean Scorpionfish, Bahamas (Ocean Frontiers Dive Shop)

THESE SCARY MONSTERS MUST BE HUGE, RIGHT? I’M KEEPING OUT OF THE WATER

Not so fast. When all is said and done – and in my view, most disappointingly – adult Caribbean Scorpionfish grow in the range of… erm… 7 – 14 inches. So now you are reassured, here’s a great short video from Ocean Frontiers Dive Shop, who kindly shared it on YT. I’ve used a couple of illustrative stills from it too.

ANYTHING ELSE WE NEED TO KNOW?

I can do no better than to turn to Card 81 to the excellent Monsters of the Deep‘ series of trading cards (the link is to my MotD page). I do realise that this is a rather unscientific approach. On the other hand these guys pack memorable information into a very short space, and do it well. Note that you can get a reflex sting from a scorpionfish for up to a week after it has died. Eat dust, earthbound scorpions.

Credits: Melinda Riger / Grand Bahama Scuba (1, 2, 3, 4,); Ocean Frontiers Dive Shop (video from YT, 2 stills); Wierd (sic) Creatures / Monsters of the Deep (O/S)

Scorpionfish, Bahamas (Ocean Frontiers Dive Shop)

FORAYS WITH MORAYS (5): THE GOLDENTAIL


Goldentail Moray Eel (Melinda Riger / G B Scuba)

FORAYS WITH MORAYS (5): THE GOLDENTAIL

The Goldentail Moray Eel Gymnothorax miliaris is one of the half-dozen moray species found in Bahamas waters. Adults range in length from about 1.5 to 2.5 feet, and they are creatures of the reefs and rocks of the western Atlantic. As far as I can make out, the goldentails are rather less common than green or spotted morays, the two main eel species of the Bahamas.

Goldentail Moray Eel (Melinda Riger / G B Scuba)

Like their moray cousins, goldentails likes to keep themselves to themselves, and lead largely solitary lives. That said, sometimes they have been observed hunting in a group. They live in holes, clefts, and caverns which they leave both during the day and at night to hunt for prey along the reefs, aided by an acute sense of smell. Their diet is mainly of crustaceans, mollusks, and small fishes. 

goldentail-moray-eel-istock-getty-images-2

ARE GOLDENTAILS DANGEROUS?

Like many other eels, goldentails secrete a protective mucus that contains a toxin, making them unattractive prey for large predators such a groupers and barracudas. They are also associated with ciguatera poisoning, the active ingredients of which are found in the mucus coating. They are sometimes found in aquariums – the associated sites give a warning of painful bites, because they have backwards-pointing teeth (aka prey traps) – see header image for a clear view of this.

Goldentail Moray Eel (Melinda Riger / G B Scuba)
 
CAN YOU EAT THESE FISH?

Well I wondered that too, so I checked. The answer seems to be yes, if you real really want to. Comments on forums include:

  • “Yes they are edible, I just ate one few weeks ago. Some parts are little bony and skinning it is a bitch. But the meat is very soft and white, delicious. Deep fry works”. 
  • “After eating our moray eel something changed. The next morning, we were decidedly feeling ill. I won’t get into the details, but let’s just say that “gastrointestinal effects”
  • “…symptoms (of ciguatera) include gastronomic effects, and neurological effects which include headaches, numbness, paresthesia, muscle ache, and even hallucinations”.
  • “Before you can eat one you have to kill it. They are amazingly hard to kill. I would skip it.”
  • “I would rather eat a shoe”

So I’ll be moving straight on to the next course, please. Or just a Kalik would do, thanks.

goldentail-moray-eel-istock-getty-images-3

RELATED POSTS

SPOTTED MORAY EELS

GREEN MORAY EELS

goldentail-moray-eel-istock-getty-images-1.

Credits: Melinda Riger / Grand Bahama Scuba (1, 2, 4); iStock / Getty Images (3, 5, 6)