I’ve gone pictorial for today because I have only got my phone with me while we are away. Composition is slow, close to decomposition – and the comms connection is close to disconnection
Blue chromis (Chromis cyaneus) belong to the same group of fishes as damselfishes. These unmistakeable, bright reef denizens are very visible despite their tiny size. These fish are shoalers, so out on the reef you can enjoy them flickering around you as you swim along or hang in the water to admire the corals.
Like many a pretty and easily captured small fish that can be monetised once removed from its natural home environment, the blue chromis is popular for aquariums, and for humans to keep in their own home environments, unselfishly feeding them concocted food.
Blue chromis are adaptable and sociable, and will happily swim with other small reef fishes (as above). My own favourite combo is chromis mixed in with sergeant majors. But a shoal of them (mostly) alone is pretty special too….
I cynically mentioned ‘concocted’ food earlier. Here is one online care instruction for looking after them: “They are omnivores, meaning that they eat both meaty and plant based foods. They are not difficult to feed and will eat a variety of regular aquarium fare, frozen, live, and sometimes even dry food. Feeding them a variety of foods will help them retain their color in captivity. They sometimes feed on the algae in the tank”.
If you are tempted to rescue some from their reef habitat, rest assured that: They have been known to spawn in captivity. Blue chromis can usually be obtained for about $10-15. And don’t hold back on the frozen food (though maybe warm it up a bit before feeding time).
Credits: Melinda Rodgers / Dive Abaco; Melinda Riger / G B 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.
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.
“I’m so glad we agreed to watch each other’s backs…”
Meet Nurse Betty, as she is known to divers
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.
Spot the REMORA hitching a ride on this shark’s back
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’
GULAR SACS: SCRATCHING THE SURFACE OF AN IN-DEPTH VIEW…
A half-way intelligent microbe would make a better job of getting the internet into our home than the current ISP that nominally serves, at some expense, Maison Harbour. So I am restricted to posting 2 fantastic photos of gular pouches as a tempter for things to come when the dimwits in charge of the ‘provision’ of ‘service’ of ‘internix’ locate the act that they need to get together.
Spoiler Alert: ‘Gular Sacs’ has nothing to do with modern jazz. You need to go somewhere else for that…
Photo credits (if they load in the next fortnight or so): Phil Lanoue; Franz Delcroix – with thanks for use permission
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.
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.
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.
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.
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.
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
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.
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
It’s often a hard decision whether to include a short piece of video footage in a post. By short, I mean less than a minute. On the one hand, there is usually a good reason for inclusion, even if only aesthetic. On the other, it simply takes up more time for busy people who may prefer to flick through an article and enjoy some nice images along the way. Today, you can have the best of both worlds.
Sanderlings are definitively ‘peeps’, a group name that embraces the smallest and squeakiest sandpiper species. They are the wave chasers, the tiny birds that scuttle along the beach, into the retreating tide for a snack from the sand, and back to the beach again as the waves creep in. Their little legs and feet move in a blur, and many people immediately think of wind-up clockwork toys as they watch the birds in action.
One of the joys of being a sanderling is that rock pools fill and empty diurnally. At some time during daylight, there’s the certainty of a quick dip. I was lying on the beach when I took this short video, so that I didn’t spook the birds. I was equipped with a smallish camera (I drowned it the following day. By mistake I mean) but I kept my distance rather than try to get closer and spoil their joyful bathing.
I caught these little birds at a critical moment. You can tell that the tide is coming in fast. The peeps are becoming edgy, and weighing up the joys of immersion in a pool with the less enjoyable prospect of being washed out of the pool by the next wave. Within a minute or so, they had all flocked down the shoreline for a foraging session.
Waves and incoming tide getting a little too close for comfort on the edge of the pool…
Next to the migratory PIPING PLOVERS that favour Abaco as their winter home, the wave chasers are my favourite shorebirds. My keenness on them killed my camera. I went out into the incoming waves to get shots back at the beach with the sun behind me. Great idea until I lost my balance with, as they say, hilarious consequences. Lesson learnt – never turn your back on waves.
I’ve recently had a flood of online hits for a creature I wrote about several years ago. It’s an aggressive-looking insectthat I found in the coppice on South Abaco. I have revisited and revised the original article, with some better images than my own original ones. I could only get a partial shot of the insect, and I wondered whether to try to reach it and get a more complete shot. Perhaps I could have, but very fortunately for for me (as it later turned out) I didn’t touch it.
This creature turned out to be a Spider Wasp (aka Pepsis Wasp), of the Pompilidae family. The insect is familiarly known as a Tarantula Hawk, for reasons give in unsparing detail below. For it turns out that this creature would be the hardest bastard insect on Planet Bastard in the Galaxy Bastardium.
It’s lucky that I didn’t try to try to collect it to keep it in a matchbox (if those even exist now). Note, for start, the scary eating apparatus… and it’s not for nibbling leaves as I had thought, but chopping up small insects. The leg claws and barbs are for pinning down its prey. You would not believe how unpleasant these little buddies are – and that’s before we even mention the sting…
SPIDER WASPS IN ACTION
These wasps are known in some countries as “horse-killers”. There are many species around the world, with 6 subspecies, one of which being the Tarantula Hawk or Pepsis Wasp – so-called because it hunts tarantulas and uses them in a most ingenious and cruel way… NB theBNT have rightly pointed out that these insects are unaggressive to humans. If you leave them alone, they will spare you. I’ve also read that“The tarantula hawk is relatively docile and rarely stings without provocation”Now read on to see if it might be sensible to provoke one or not.
SCARY CRITTERS & LIVING LARDERS
(Trigger Warning: this is really rather gross)
SPIDER WASPS are ‘solitary’ insects that feed on ground spiders/ tarantulas by stinging them to paralyse them, then eating them. In the most sinister way, the females also make use of spiders for breeding purposes. Hear this! They build a nest in a burrow, find a spider (a tarantula for choice), paralyse it with their sting, drag it to the nest and lay a single egg on its abdomen. Then they seal up the burrow.
When the egg hatches, the larva chews a hole on the spider’s abdomen and enters a living larder. It gradually eat its host as it grows. The spider’s vital organs are left till last, so that the spider stays alive as long as possible until the larva has reached full-size. After several weeks, the larva spins a cocoon and pupates (often over winter). Finally, the wasp becomes an adult, bursts Alien-like from the spider’s abdomen (deftly evading Ripley), and tunnels out of the burrow…
Do NOT try this at home or more than 10 yards from a medical centre
SPIDER WASPS: MORE FEARFUL FACTS
Their hunting improves with experience – the more spiders they eat, the quicker they find, attack & kill them
Males use ‘perch territories’ to scan for receptive females from a tall plant or other vantage point, a behaviour known as HILL-TOPPING
Adult wasps also feed on a variety of plants for nectar & pollen. They may become intoxicated on fermented fruit, which affects their ability to get around (I think we’ve all been there at some time…)
The female Pepsis gets her spider in two main ways: approaching a tarantula causing it to rear up defensively on its legs, thus exposing its abdomen to the sting or
She locates a tarantula’s burrow, using her sense of smell. She tricks the spider into emerging by tweaking the web at the burrow’s entrance or ‘intruding’ (see video below)
The wasp uses her long stinger to stab her prey. The poison rapidly paralyses the spider. She then drags it to her burrow, lays her egg onto the tarantula’s abdomen, seals the burrow and leaves. Job done
The hooked claws and barbs on the wasps’ long legs are weapons for grappling with victims
The stinger of a female tarantula hawk can be up to 7 mm (1/3 inch) long – and the sting is among the most painful insect stings in the world (see below)
Only the females sting (males may pretend to) because the stinger is linked to the ovipositor (egg-laying organ)
You can distinguish females from males by the curled antennae of the female. Mine was therefore female
The Pepsis wasp has (unsurprisingly) very few predators, though apparently roadrunners and bullfrogs may tackle them
Here is a hypnotically fascinating 3-minute video of the life-or-death struggle
SPIDER WASP –v- TARANTULA
THE STING
The sting of these wasps is among the most painful of any insect, though the most intense pain lasts on a few minutes. Entomologist Justin Schmidt bravely submitted himself to the stings of various insects and described this pain as“…immediate, excruciating pain that simply shuts down one’s ability to do anything, except, perhaps, scream. Mental discipline simply does not work in these situations.”
Schmidt produced his SCHMIDT STING PAIN INDEXThe pain scale, based on 78 species, runs from 0 to 4, with 4 awarded for the most intense pain. Spider Wasps of the species Pepsis – i.e. Tarantula Hawks – have a sting rating of 4.0, described as“blinding, fierce, shockingly electric. A running hair drier has been dropped into your bubble bath”Only the bite of the Bullet Ant – and the sting of the Warrior Wasp – is ranked higher, with a 4.0+ rating, vividly described as“pure, intense, brilliant pain. Like fire-walking over flaming charcoal with a 3-inch rusty nail in your heel”
LIGHT RELIEF AFTER THE PAIN
1. In 1989, New Mexico chose the Tarantula hawk wasp as the official state insect. The choice seems to have been left to schoolchildren and I’m guessing here (or gender-stereotyping) but I suspect it was the boys’ choice that won…
2. Tarantula Hawk is a “psychedelic progressive metal band” from San Diego, Ca. Their short discography includes their debut Tarantula Hawk (CD/LP, 1998); Burrow (Live CD, 2000, self-released); and Untitled. The cover of their debut provides the perfect ending for this post, vividly depicting the colour and texture of the swirling fiery pain you could experience (and I don’t really mean from listening to the music…)
I featured the extraordinary, colour-transforming PEACOCK FLOUNDER Bothus lunatus about 3 years ago in the Bahamas Reef Fish series (No. 21 I think). These really are remarkable creatures, and I am pleased to be able to show some more wonderful illustrative photos.
ROVING EYES
In the fish shown here, you’ll see that – surprisingly – both eyes are on the upperside of the fish, above the rather grumpy mouth, whereas the head is horizontal to the ocean floor. Oddest of all, juveniles are constructed conventionally with bilateral eyes, and look like ‘normal’ fish rather than flatfish.
As the fish matures, in some magic way the mechanics of which I can only guess at**, the right eye grows round to the topside and the flounder transforms from a ‘vertical’ fish to a flatfish. For this reason, the PF is known as a ‘lefteye’ flounder. Maybe in other flounder species in the world – the southern hemisphere maybe? – the eye that moves round to the upperside is the left eye.
The eyes of this fish have another special trick up their sleeves (so to speak). They operate completely independently. Thus the creature can look left and right, or forwards and backwards, simultaneously. It’s an excellent system for detecting predators coming from any angle. It’s a superpower we might all benefit from.
DO THEY HAVE ANY OTHER TRICKS WE SHOULD KNOW ABOUT?
Yes they do indeed. If you have been admiring the fish shown so far, you’ll have noticed that the colour of each one differs from the others. In addition to the predator-protection that the eyes provide, the peacock flounder can make itself (near) invisible. They can rapidly change colour to match their surroundings. There are 3 reasons for this: to avoid / confuse predators; to conceal themselves on the sea-floor to catch passing prey; and, as dive expert Fred Riger has pointed out, “the male peacock flounder can, and does greatly intensify his colours to declare territory and attract females. When doing this the males will also signal with the left pectoral fin, sticking it straight up and waving it around.”
The same fish, photographed over several minutes as it moves over the ocean floor
Matching the background happens as the fish swims, and in a few seconds. When they rest on the sea-floor, the camouflage may even become total. In #4 above you can just about make out the eyes. The whole effect is known as ‘cryptic coloration’ or CRYPSIS. In contrast, the image below shows just how adaptable the transformation can be. Note how the fish can even mimic the pinkish tinge of the sand perfectly. If threatened, the fish will bury itself in the sand, with just its eyes showing.
HOW DO THEY MANAGE TO CHANGE COLOUR IN SECONDS?
It’s complicated! A simple answer is: a mix of hormones, pigment-cells and vision, all coordinating rapidly. The colour change works in two ways: pigments are selectively released to the skin cells; and other pignments can be selectively suppressed. An analogy might be image manipulation using variations in brightness, saturation etc. Not convinced? Then watch this short video and prepare to be impressed. Astonished, even.
WHAT IF A FLOUNDER CAN’T SEE CLEARLY FOR SOME REASON?
As with many (all?) superpowers, there is usually some kryptonite-style flaw. A flounder with a damaged eye, or one temporarily covered (by sand, for example) will have difficulty in changing colour – possibly at all, or at any rate with the swiftness it needs to have.
THESE SIDEWAYS FISH – HOW DO THEY… YOU KNOW…?
Take a look at the fish above with its top fin raised. It’s a ‘ready’ signal in a harem. Male flounders have a defined and defended territory within which live up to 6 females – a so-called ‘harem.’ I can do no better than borrow the description of the rituals from an article derived from scientific papers byKonstantinou, 1994; Miller, et al., 1991in the websiteanimaldiversity.org/…ounts/Bothus_lunatusTo which I can only add, ’15 seconds, eh?’
“Mating activities usually begin just before dusk. At this time, a male and a female approach each other with the ocular pectoral fin erect. The two fish arch their backs and touch snouts. After this interaction the female swims away, and the male sometimes follows, approaching the female again from the left side. At this point the male pectoral fin is erect and the female pectoral fin moves up and down, possibly signalling willingness to mate. The male then positions himself underneath the female and mating begins. This process consists of a mating rise, during which the female and male rise in the water column together. On average, these rises last about 15 seconds. At the highest point of this rise, usually around 2 m above the substrate, gametes from both fish are simultaneously released, producing a cloud of sperm and eggs. Once the couple returns from the rise, the male “checks” to make sure mating was successful, and the pair separates quickly, swimming away from each other in opposite directions. Not all mating rises are successful, and the process of “checking” is thus important. The exact purpose of the mating rise in these flounders unknown; possible reasons for rising include better dispersal of gametes and predator avoidance.”
Peacock Flounder – Kim Rody Art
**This may in fact be through sheer laziness
Credits: Melinda Riger & Virginia Cooper / Grand Bahama Scuba; Melinda Rogers / Dive Abaco; Adam Rees / Scuba Works; Kim Rody; animaldiversity.org; magpie pickings and other credits in the text
