SPONGES ON THE REEF: A COLOURFUL MISCELLANY


Brown Tube Sponge ©Melinda Riger @ G B Scuba

SPONGES ON THE REEF: A COLOURFUL MISCELLANY

It’s time to take an up-close look at some of the sponges you may find as you snorkel or scuba round the reefs of the Bahamas. I am always amazed by how bright and colourful they are, and by their many different shapes and sizes. Even the unpromising sounding (slightly medical, even?) BROWN TUBE SPONGE turns out to be fascinating to examine closely. Here are some more sponge species. 

CANDELABRA SPONGECandelabra Sponge ©Melinda Riger @ G B Scuba copy

STOVE PIPE SPONGEStove Pipe Sponge ©Melinda Riger @ G B Scuba

PURPLE VASE SPONGEVase Sponge, purple ©Melinda Riger @ G B Scuba

BRANCHING TUBE SPONGE WITH ROPE SPONGESponges - Branching Tube Sponge with rope sponge ©Melinda Riger @ GB Scuba

PURPLE TUBE SPONGEPurple Tube Sponge ©Melinda Riger @ GB Scuba

PURPLE SPONGE WITH GIANT ANEMONEPurple Sponge : Giant Anemone ©Melinda Riger @ G B Scuba

VASE SPONGEVase Sponge ©Melinda Riger @ G B Scuba

The above sponges represent a fraction of the sponge varieties found on Bahamas reefs. I’ll post some more quite soon. All this has made me want to go for a snorkel. But right now I am 30 miles from the sea. And I have no gear…

HANG ON A MOMENT! WHAT IS A SPONGE WHEN IT’S AT HOME?

It’s really very simple: if you are ever asked the question, just reply “a sponge is a primitive sedentary aquatic invertebrate with a soft porous body that is typically supported by a framework of fibres or calcareous or glassy spicules. Sponges draw in a current of water to extract nutrients and oxygen”.

AND WHAT, PRAY, IS A SPICULE?

You’re having a laugh… if you seriously want to know, read the abbreviated version about them HERE. And admire this microscopic collage of ‘demospongiae spicule diversity’ made available by the wonders of Wiki and the research of about 20 credited scientists.

Demospongiae_spicule_diversity

All photos: Melinda Riger, Grand Bahama Scuba. Tip of the hat to Wiki and scientists

HAWKSBILL TURTLES: A RARE FIND & SWIMMING WITH ANGELS


Hawksbill turtle (juv), West End Grand Bahama

HAWKSBILL TURTLES: A RARE FIND & SWIMMING WITH ANGELS

There is something unusual about this juvenile hawksbill turtle peacefully noodling round some impressive elkhorn coral with the grunts and sergeant majors. He’s a rarity. He was found at West End, Grand Bahama (just 67 miles swim from West Palm Beach Fl.), a place where hawksbills are very scarce. Loggerheads, they have. And there are plenty of hawksbills elsewhere in Grand Bahama waters. But not at the western tip. So finding this little guy and getting some good photos was a particular pleasure for Linda Cooper. And maybe the presence of a juvenile is a sign that hawksbills may begin to populate the reefs of West End, as perhaps they did historically.Hawksbill turtle (juv), West End Grand Bahama

Linda and her husband Keith run West End Ecology Tours. They have a comprehensive website HERE and a Facebook page HERE. Check it out to see how much there is to explore at West End. The birds, the corals and reef life, the starfish – and a speciality, swimming with rays. To which can now be added the chance of seeing a hawksbill turtle…Hawksbill turtle (juv), West End Grand Bahama

A DOZEN HAWKSBILL FACTS TO CHEW OVER

  • All sea turtles are classed as reptiles (something that always surprises me, somehow)
  • The top shell (carapace) consists of scales that overlap like roof shingles
  • The yellowish bottom shell is called the plastron
  • Adult hawksbills weigh around 100 pounds
  • Sea turtles sleep at night, and can stay underwater for a hours without breathing
  • Hawksbills are omnivorous, eating algae and seagrass but also sponges, urchins and small fish
  • Females lay about 100 eggs like ping-pong balls, and then at once return to the sea for good
  • The sex of baby turtles is determined by relative nest warmth – females from the top eggs
  • Baby turtles hatch almost simultaneously: all must work to dig their way out.
  • They tend to hatch at night and head straight for the sea’s phosphorescence…
  • …except that artificial lights confuse them & lead them away from the sea to likely death
  • Threats: predation, coastal development & habitat destruction, pollution, & illegal collection

SWIMMING WITH ANGELS

As I was writing this, another fact about hawksbills popped into my head. I checked through my archive – mainly Melinda Riger’s wonderful shots from elsewhere on GB – and yes, it is true. There seems to be some sort of symbiotic relationship between the turtles and angelfish. They are often found feeding together. A bit of research confirms this general observation, without giving a clear cause for it. Maybe it is simply that they eat some of the same food; and that there is plenty of it on healthy reefs so there is no cause for aggression on either side. It’s fine for a hawksbill to share with an angel.

10245Green Turtle, Gray Angelfish ©Melinda Riger @GB Scuba copyTurtle with Gray Angelfish ©Melinda Riger @ G B Scuba copyHawksbill Turtles, French Angelfish eat sponge ©Melinda Riger @ GB Scuba copyHawksbill Turtle eats sponge ©Melinda Riger @ GB Scuba copy

NOTE The Hawksbill is listed as Critically Endangered by the IUCN red list of Threatened species as its populations have declined dramatically throughout the world and especially in the Caribbean region. It is listed in Appendix I of the Convention on the InternatIonal Trade of Endangered SpecIes (CITES) meaning that Hawksbills are near extinction or very endangered. All marine turtles are now protected under Bahamian law, as is the taking of eggs.

Credits: West End Ecology Tours / Linda & Keith Cooper (photos 1, 2, 3); Melinda Riger / Grand Bahama Scuba, all other images; BAHAMAS NATIONAL TRUST  for their very useful fact-sheet (one of many) which I have adopted and adapted; Aquoflite for the vid.

JACKKNIFE FISH: BAHAMAS REEF FISH 30


Jackknife Fish ©Melinda Riger @ GB Scuba

JACKKNIFE FISH: BAHAMAS REEF FISH 30

The rather uncomfortably ‘double-k’  Jackknife fish is one of 3 types of similar drumfish subspecies of Equetus found in Bahamas waters. The others are the High Hat and the SPOTTED DRUMFISH – the first fish featured in this series. Each of these drumfish species has juveniles that are elegant and delicate, becoming more conventionally fishlike as they grow to adulthood, as the final image shows.

Jackknife fish (juv) ©Melinda Riger @ G B Scuba copy

I always want to stick a hyphen in to separate each k: jack-knife fish. I think it’s an English thing. I have seen, at the other extreme, ‘jack-knifefish’, which looks most weird of all. Checking online, jackknife fish wins by a distance as the correct spelling. 

Jackknife Fish (juv) ©Melinda Riger @GB Scuba

These little fish, typically between 6 and 9 inches, inhabit the coral reefs of the Caribbean, the Gulf of Mexico, Florida and the Bahamas. Juveniles eat plankton and similar organism, graduating to small crabs and shrimps as adults.

Jackknife Fish ©Melinda Riger @ G B Scuba

A FULLY GROWN JACKKNIFE FISH (NOAA)Jackknife fish adult_NOAA_Photo_Library

Like other drumfishes, the jackknife can produce ‘croaking’ or ‘drumming sounds. This involves the fish beating its abdominal muscles against its swim bladder. There’s a lot more to it than my rather simplistic summary, but it’s probably as much as anyone needs or wants to know… The primary reason is believed to relate to mating. Other reasons include ‘low-level aggression’, and keeping in touch with each other in turbid waters.  I prefer the unscientific theory that sheer happiness makes them croak. Here’s a short video of a happy juvenile Jack knife fish (that’s yet another spelling variant…)

RELATED POSTS

Credits: Melinda Riger / GrandBahama Scuba; NOAA

WTF? (WHAT’S THAT FISH) 10: FLYING GURNARD


Flying Gurnard (Adam Rees / Scuba Works)

WTF? (WHAT’S THAT FISH) 10: FLYING GURNARD

Imagine that you are swimming along resplendent in your snorkelling gear (me) – or in scuba gear for the advanced swimmer (you). There, below you, camouflaged against the sea bottom is a fish. A strange-shaped brown sort of creature with odd side fins. As it progresses over the gravelly sand, your immediate reaction is ‘what the…?’ Its fins seem to be turning into… wings. Like this:

Flying Gurnard (Adam Rees / Scuba Works)Flying Gurnard (Adam Rees / Scuba Works)Flying Gurnard (Adam Rees / Scuba Works)

Yes, it’s a flying gurnard. Unlike flying fish, it can’t actually fly through the air. But once its wings are fully spread, it certainly looks as though it could.

Flying Gurnard (Adam Rees / Scuba Works)Flying Gurnard (Adam Rees / Scuba Works)

WHAT’S THE POINT OF THE WINGS IF THE THING CAN’T FLY?

This gurnard species usually gets around using its ventral fins as ‘legs’, with the pectoral fins (‘wings’) close to the body. There seem to be several possible reasons for possessing the ‘sudden-deployment-of-flashy-wings’ superpower. 

  • It surprises and deters predators by movement, turning prospective prey into an apparently different creature
  • Bright or lurid colouring may be a deterrent warning of a foul-tasting or poisonous species  (APOSEMATISM)
  • A creature may actually be harmless and even tasty (as here) but may appear to be unpalateable or poisonous (BATESIAN MIMICRY)
  • In any event, the wings enable the fish to take off from the sea bottom and travel faster by ‘flying’ thought the water to escape a predator

Dactylopterus_volitans Flying Gurnard (cralize wiki)

I had a quick look to see how  scientists in history had depicted this extraordinary fish. The earliest illustration I could find was taken from “Allgemeine Naturgeschichte der Fische (General natural history of fishes),” a 12-volume encyclopedia by author/illustrator Marcus Elieser Bloch (1723-1799), which described all fish species then known to science (and 267 previously unknown) (© AMNH\D. Finnin) sourced from ‘Hyperallergic’
Flying Gurnard

Here’s a short video of a flying gurnard on the move, from ‘Sia Big Fish’

Credits: All main images Adam Rees / Scuba Works with many thanks, except final one ‘cralize wiki’; Hyperallergic for the historic image; Sia Big Fish for the video

CONCH QUEST: ABACO’S MOST VERSATILE GASTROPOD


Conch Shells, Sandy Point, Abaco

CONCH QUEST: ABACO’S MOST VERSATILE GASTROPOD

The conch. Such a fascinating gastropod, and with so many uses both culinary and decorative. In certain cultures, religiously significant. A rudimentary musical instrument for a shell.  And did I mention delicious? 

Live conchs enjoy motoring around uninhibitedly on the sea floor, keeping an eye out…Conch on the move ©Melinda Riger @ G B Scuba copy Conch Man-o-War Cay, Abaco (Charmaine Albury) copy Conch in shell ©Melinda Riger @ G B Scuba copy

Conchs also enjoy racing each other…Conch race ©Melinda Riger @ G B Scuba copy

“Eat my dust…”Conch Trail ©Melinda Riger @ G B Scuba copy

Conch Pearl – one of the rarest natural pearls in the worldConch Pearl (Ambergris Caye Beize)

A conch spiral close-up

Conch close-up, Abaco (Rhonda Pearce)

Conch shells just lie around the place at Sandy PointConch Shells, Sandy Point, Abaco (Keith Salvesen) 2Conch Shells, Sandy Point, Abaco (Keith Salvesen) 3

Conchs are widely used for serving cocktails or as ashtrays in the best beach bars*Conch Shells, Abaco (Keith Salvesen) 1

*This is a lie. Sorry about that. I meant to say “make prefect table decorations”

Image credits: Keith Salvesen / RH (1, 9, 10 ,11); Melinda Riger / GB Scuba (2, 4, 5, 6); Charmaine Albury (3); AmbergrisCaye.com (7); Rhonda Pearce (8) 

WTF? (WHAT’S THAT FISH) (9): THE HARLEQUIN BASS


Harlequin Bass ©Melinda Riger @ G B Scuba copy

WTF? (WHAT’S THAT FISH) (9): THE HARLEQUIN BASS

I’m conscious of being rather unfair on this pretty dwarf bass species by including it in the WTF? series. The usual denizen of the series is a fish so strange that one’s immediate instinct is to yell into one’s facemask, “WTF?”. BATFISH or FROGFISH or GUITARFISH and their bizarre ilk. So with apologies to this species for its somewhat harsh classification, here are some quite flattering photos of it to make up for any hurt feelings.

Harlequin Bass Fish ©Melinda Riger @ G B Scuba copyHarlequin Bass (jpc what'sthatfish)

The Harlequin Bass Serranus tigrinus has unusually striking body markings and a rather endearing spotty tailfin. They are hardy creatures and I note that they are recommended aquarium fish “and make a great candidate for beginners”, though there are warnings that they are “semi-aggressive”. NB they are only a few inches long, so no need to panic.

Harlequin_Bass_Serranus_tigrinus wikiHarlequin_Bass_(Serranus_tigrinus) wiki

If you are still not confident that you can ID one in the wild, here is a short video… Actually I’m really including it to show how these fish swim around. And next time, I promise a truly eye-watering WTF? fish from Bahamian waters, though its camouflage is so good that you may never notice it…

Credits: Melinda Riger / Grand Bahama Scuba (1, 2); jpc/ what’s that fish; wiki

REMARKABLE REEF CREATURES TO ADMIRE


Octopus (Adam Rees : Scuba Works)

REMARKABLE REEF CREATURES TO ADMIRE

Here is a small collection of recent photographs from Adam Rees of Scuba Works. Three OCTOPUSES, an astounding FROGFISH,  a SEAHORSE, a MANTIS SHRIMP at close quarters, and a wonderful HAWKSBILL TURTLE. Clicking on a link will take you to a post with more photos and information about each creature. If these images don’t make you want to scuba then… what will?

Frogfish Hunting (Adam Rees : Scuba Works)Seahorse (Adam Rees : Scuba Works)Mantis Shrimp (Adam Rees : Scuba Works)Octopus 3 (Adam Rees : Scuba Works)Hawksbill Turtle (Adam Rees : Scuba Works)Octopus 2 (Adam Rees : Scuba Works)

All photos Adam Rees / Scuba Works, with thanks for use permission