Happy Holidays from The Right Blue!

Christmas Tree worm (Spirobranchus giganteus) and Pillar Coral (Dendrogyra cylindrus), with polyps extended

by B. N. Sullivan

We chose this image for our holiday post because we thought it looked festive. We hope you agree.

The photo, taken during a night dive off  Providenciales in the Turks and Caicos Islands, shows a stand of Pillar Coral (Dendrogyra cylindrus) with its polyps extended for feeding.  Nestled cozily in the coral is a kind of Polychaete worm called the Christmas Tree worm (Spirobranchus giganteus).  The worm burrows into coral and secretes a calcareous tube in which it lives.  Only its pair of feathery 'Christmas Tree' shaped crowns are visible outside its tube. The feathery tentacles on the crowns trap tiny tidbits of food, and also are used for respiration.

The Christmas Tree worm can retract its crowns into its tube for protection.  When the crowns retract, a structure called the operculum closes snugly over the tube like a lid or a little trap door.  Christmas Tree worms come in lots of colors: red, orange, yellow, blue, and white. We also have seen a version that is striped!

We hope all of our readers are enjoying the holiday season, and we wish you all a very happy, healthy, and prosperous New Year.

It's a Pipefish, but which Pipefish?

Unidentified Pipefish, Fukui Point, Bunaken Island, Indonesia

by B. N. Sullivan

Nature photographers sometimes find it difficult to positively identify a creature they have photographed in the wild.  Certainly those of us who began taking pictures of critters in pre-Google days had (and still have) shelves full of reference books that we pored over, looking for photos or descriptions of animals we were trying to identify.  Nowadays, the task is made easier due to the wealth of online materials, searchable databases, and so on.  Still, many online photos are misidentified, so the trick is to find authoritative sources.

Generally, large animals and very common animals are easier to identify, while small, and/or less common creatures still can present a challenge.  Relying solely on an animal's coloration or markings to identify it does not always work.  For many species, the males and females look quite different.  As well, many creatures undergo drastic changes in appearance as they progress through their various developmental stages.  In some cases, similar species can be distinguished from one another only through laboratory examination of structures not visible externally.

But I digress...

This is a about a pipefish.  Recently, The Terramar Project published an article about a pipefish photo that prompted some marine scientists to think that it depicted a new species.  The article reminded me that I had a pipefish photo, taken many years ago, that I had never been able to identify with certainty.

That's my mystery pipefish at the top of the page.  To me, it resembles the so-called Network Pipefish (Coryichthys flavofasciatus), but may not be an exact match.  Now, perhaps the resolution of the photo is not as crisp as it could have been.  The markings thus may not be clearly represented.

But if anyone knows with a fair degree of certainty what Pipefish species is in my photo, please let us know.  Leave a comment or send us a tweet: @TheRightBlue

For the record, the fish was photographed (on film) at Fukui Point, Bunaken Island, in Indonesia's Bunaken National Marine Park -- in 1993!

Hold that pose, little crab!

Yellowline Arrow Crab, getting situated on a sponge

A Yellowline Arrow Crab strikes a pose

by B. N. Sullivan

This series of photos depicts a Yellowline Arrow Crab (Stenorhyncus seticornis), a common Caribbean species.  With its distinctive pointy-headed spidery shape, bulging eyes, yellow knees and tiny purple claws, it is an interesting photo subject.  As we approached this individual, it skittered onto a bright orange sponge -- also quite photogenic.

But crabs are not always the best photo models.

In this instance, the crab first struggled to get situated on the sponge, as if it wasn't quite sure how to arrange all of those gangly legs.  A few moments later it was settled in place, and I snapped its portrait.

I began to move around a bit, hoping to catch it from a slightly different angle, but my crabby friend would have none of it.  Without a by-your-leave, the crab simply left the scene.

It was time to look around for another subject.

"I'm outa here...!" - Yellowline Arrow Crab

I took these photos of the Yellowline Arrow Crab during a night dive at Little Cayman Island.

Bearded Scorpionfish: A Name That Suits

Bearded Scorpionfish (Scorpaenopsis, barbatus), Red Sea

by B. N. Sullivan

Meet the Bearded Scorpionfish (Scorpaenopsis barbatus).  Both the common and scientific names of this fish refer to the frilly, fleshy flaps of skin protruding from its chin.  (The Latin name "barbatus" translates to "bearded.")

Like others in its family, Scorpaenidae, the Bearded Scorpionfish is an ambush predator.  Its strategy is to lie in wait for its prey to come swimming past at close range, and then to spring forth with its mouth wide open to engulf its meal in one big gulp.  In order to do this successfully, it helps to be as inconspicuous as possible.  It helps to be camouflaged.

The scorpionfish usually rests on algae-covered rocks, or among corals and marine plants.  The frills on this guy's chinny-chin-chin are a part of its disguise, helping it to blend in with its usual surroundings.

Despite its elaborate camouflage, the individual in these photos was easy to spot since it was out in the open, resting on a patch of sand.  Hoping I could get a close-up photo of its head, I lay down on the sand, too, and inched toward the fish.  To my delight, my subject did not flinch or flee after the first shot, so -- still on my belly --  I was able to move around carefully and face him to take a head-on shot of his impressive 'beard' at close range.

Bearded Scorpionfish (Scorpaenopsis, barbatus), Red Sea

A Beautful, Fragile Bryozoan Colony

Macro photo of a Lace Bryozoan (Reteporelina denticulata)

by B. N. Sullivan

This beautiful marine organism is a colony of Lace Bryozoa (Reteporelina denticulata).  Despite their appearance, Bryozoans are neither a coral nor a plant.  Taxonomically, the Bryozoa form a phylum all their own.  Most of the more than 4,000 species of Bryozoans live in the sea.

The name Bryozoa translates to "moss animal."  The individual animals that make up the colony are microscopic.  This species builds lacy calcareous structures of interconnected branches, made from the mineralized exoskeletons of thousands of tiny individuals.  The macro photo at the top of this page gives a good idea of how intricate and intertwined the branches can be.  It takes the colony of organisms a very long time to build these lovely structures.

The colonies are pretty, yet they are quite brittle and therefore very fragile.  If you come across a Bryozoan colony while diving, be careful not to touch it or bump it. The delicate structures will almost surely break if handled.

Almost all Bryozoans are sessile -- that is, the colonies are attached to some hard substrate like rock or hard coral.  The photo below shows a colony of Reteporelina denticulata growing on a hard coral (Porites lobata).  Once in awhile, a diver may come across a small Bryozoan colony that appears to be growing out of packed sand or mud, but closer inspection will almost certainly reveal that it is in fact attached to a rock or lump of coral rubble that is buried.

The Bryozoan species pictured here is rarely seen at depths of less than about 10 meters, but we have seen them on rocks below 40 meters.  In our experience, larger colonies are found at deeper depths -- perhaps because they are less likely to be disturbed and damaged by surge.

I photographed the Lace Bryozoan colonies shown here off the coast of Puako, Hawaii at depths between 20 and 30 meters.  The colonies pictured here are quite large for the species -- approximately four inches (10 cm) across.

Lace Bryozoan colony growing on coral in Hawaii

Basking Sea Turtles in Hawaii

Green Sea Turtle (Chelonia mydas), basking at Puako, Hawaii

by B. N. Sullivan

Imagine that you are in Hawaii, walking along near the edge of the ocean.  You come upon a sight like that in the photo at the top of this page -- a sea turtle lying on the sand or on the rocks.  You may notice that its carapace is dry, indicating that it has been out of the water for awhile. You may feel alarmed, wondering if it is stranded.  You think: Maybe a wave washed it ashore and it doesn't know how to get back into the ocean. Or perhaps it crawled out of the water intending to nest, but got stuck.

If it is a Green Sea Turtle (Chelonia mydas),  chances are very high that it has come ashore intentionally, it is not distressed or stranded, and it is not about to lay its eggs.  It is engaging in a behavior called "basking" -- another term for sun-bathing.

So far as anyone knows, only green sea turtles engage in this behavior, although no one is certain why they do it, or why they are the only sea turtle species who like to bask.  One proposed explanation for basking has to do with temperature regulation, since other kinds of reptiles are known to do this.  Another hypothesis is that basking ashore allows the turtles to rest for relatively long periods of time (hours) without risking predation, e.g., by sharks.

Regardless of the reason, Green Sea Turtles do come ashore regularly in many locations in the main, human-populated, Hawaiian islands, none of which are known to be nesting areas for this species.  They come ashore to bask in the sun.

So, if you come upon a turtle on the beach or rocks near a shoreline in Hawaii, what should you do?  You can watch them for awhile if you like -- just don't get close enough to disturb them.  You can photograph them, but please don't use a flash.  Don't try to move them or "help" them back into the ocean.  They need no assistance: when they are ready to go back to sea, they will do so unaided.  So don't block their path to the water, either!

Here are a couple more photos of basking turtles.  The first shows one turtle already basking while a second is preparing to "haul out."  The final photo shows a turtle who apparently has decided she has worked on her tan enough for the day, and is returning to the water.

Green Sea Turtles near the water's edge in Hawaii

A Green Sea Turtle returning to the ocean after basking

All of the basking sea turtles on this page were photographed at Puako, on the west coast of the Big Island of Hawaii.

For more information about this behavior of sea turtles in Hawaii, see:

Whittow, G.C., & Balazs, G.H. (1982). Basking behavior of the Hawaiian green turtle. Pacific Science, 36(2), 129-139 -  (11-page PDF)

Droopy Gorgonian Sea Plume - Needs Water??

Gorgonian Sea Plume (Pseudopterogorgia sp)

by B. N. Sullivan

We were swimming along the pretty reefs off the coast of West Caicos in the Turks and Caicos Islands, looking for things to photograph.  I spotted this Gorgonian Sea Plume at the edge of a patch reef.  The first thing I noticed was that it was quite tall -- with a height  of about two meters.  But the thing that really struck me was how droopy its branchlets looked. The spontaneous thought that popped into my head was that it looked like a large house plant that someone forgot to water!

That was a silly thought, of course, and it made me chuckle to myself at the time.  But when we were reviewing the photos I had taken on that dive, Jerry looked at this one and immediately said, "Hmm, needs water."  I told him I had thought the same thing when we were out there on the reef, and we both had a laugh about that.  So, from the start, our title for this photo has been "Needs Water."

Cerianthids: Marine animals that look like flowers

Cerianthid "tube anemone" - Hawaii

by B. N. Sullivan

The creatures pictured here look like anemones, but they are not true anemones.  They are Cerianthids, commonly referred to as ‘tube anemones’, which are taxonomically quite distinct from true anemones.

Cerianthids and true anemones do belong to the same phylum, Cnidaria, and the same class, Anthozoa, but tube anemones belong to the subclass Ceriantipatharia, a taxon that also includes the so-called ‘black corals’ (Antipatharia).

Dark-colored Cerianthid, Hawaii

One of the visible features that distinguishes Cerianthid tube anemones from true anemones is the morphology of their tentacles.  Cerianthids have shorter tentacles in their centers, and longer tentacles around the margin.  The color of the shorter tentacles usually is different from that of the longer tentacles, making them look a lot like flowers (at least to me).

Side view of a Cerianthid, showing its tube

Cerianthids dwell inside a rubbery tube (thus the name tube anemone) which is built from mucus secreted by the animal.  The tube is embedded in mud or packed sand. When not feeding, or when disturbed, the animal retracts inside its tube for protection.

These creatures can be difficult to photograph for several reasons.  Most Cerianthids are relatively small; their crowns of tentacles are perhaps 5 cm (2 in) across, so it’s necessary to get very close to them in order to photograph them.  If the photographer accidentally touches one of the tentacles, piff! the critter retracts.  And although Cerianthids happily feed in gentle currents, any nearby turbulence — like that created by the photographer as he or she moves about — causes the critter to quickly go into hiding.

These tend to be deep-dwelling creatures — all of the examples in this post were photographed at depths greater than 40 meters (130 ft).  They are accustomed to low levels of ambient light at those depths, so Cerianthids do not take kindly to blasts of artificial light from a camera strobe.  At best, one or two shots of an individual is all that a photographer can hope for before all that is left to photograph is the tube!

Cerianthid retracted into its tube

All of the Cerianthid tube anemones pictured in this post were photographed off the west coast of Hawaii’s Big Island.  This post was adapted from an article I wrote several years ago for ScienceBlogs.com.

Scarlet Hermit Crab from the Cayman Islands

Scarlet Hermit Crab (Paguristes cadenati), Cayman Islands

by B. N. Sullivan

Many small crustaceans look quite similar to one another, but it's hard to misidentify this little hermit crab.  A denizen of reefs in the Caribbean Sea, the brilliant coloring of the Scarlet Hermit Crab (Paguristes cadenati) sets it apart from other hermit crab species of that region.

These little crabs (about an inch long) inhabit old gastropod shells, and for some unknown reason, the shells they choose as their portable houses usually are pretty cruddy looking.  The one in the photo on this page is covered with a layer of coralline algae so thick that it almost looked like a stone, rather than a seashell.

Like many hermit crab species, these little guys are difficult to find during daylight hours.  At dusk they emerge from their hiding places in the reef and go about foraging for their food.  We spotted this individual during a night dive at Little Cayman island.

Most often, divers see only the crab's red legs and pale eyestalks poking out of the aperture of the shell in which they live.  This individual was cruising along across some coral, so we got to see a bit of the pretty speckled markings on its back, too.

The Scarlet Hermit Crab is a member of the Diogenidae family.  Comprised of more than 400 known species, the Diogenidae are the second-largest family of marine hermit crabs.

Hunting Together: A Bar Jack and a Southern Stingray

A Bar Jack and a Southern Stingray hunting together

by B. N. Sullivan

We spotted this pair of hunters in the Caribbean.  The dark colored fish in the photo is a Bar Jack (Caranx ruber). This fish makes its living as an opportunistic feeder.  In this instance, it is swimming a little above and behind a Southern Stingray (Dasyatis americana) hoping to snag a free lunch.

The stingray finds its food by rummaging in the sand, looking for little creatures to eat -- worms, small clams, tiny crabs, and such. To locate its prey, it fans away the top layer the sand by fluttering the wing-like tips of its body disc.

The crafty Bar Jack follows closely, letting the stingray do the excavating.  If the stingray uncovers something that looks tasty to the Bar Jack, the jack will snatch it in a lightning strike, then resume its position keeping watch over the stingray's shoulder, as it were.

We've seen Bar Jacks throughout the Caribbean.  In addition to pairing with hunting stingrays, we've also seen them following goatfish -- another species that digs around in the sand and rubble for food. 

By the way, the Bar Jack doesn't always look so dark. When it's not feeding, it is a handsome silvery blue color, with a black bar running along its back from its dorsal fin down to the lower lobe of its tail fin like a racing stripe.

Find the lobster in this photo

Sculptured Slipper Lobster (Parribacus antarcticus), Hawaii

by B. N. Sullivan

What you are looking at in the photo above is the ceiling of an underwater cavelet in Hawaii.  The bright red stuff is an encrusting sponge.  Most of the rest of the surface is covered by various kinds of algae.  The purplish blob in the center of all that red is not a clump of algae; it is a slipper lobster wearing a clever disguise.

This is the Sculptured Slipper Lobster (Parribacus antarcticus),  a member of the Scyllaridae family.  It is said to be the most common slipper lobster species found in Hawaiian waters, but if you polled a sample of divers there you would find that relatively few have seen these critters.  Part of the reason is that their camouflage makes them easy to miss, and their flattish profile also helps them to blend into the background.  In addition, they are rather small -- maybe five or six inches long at most.

The individual in the photos here was snuggled into a crevice in a cavelet we visited during a night dive at Puako, Hawaii.  We had been inside this cavelet many times during the day and often found pretty nudibranchs on the walls and roof surface.  Expecting that we might see some of those at night as well, we shined our lights all around as we entered.  We didn't find any nudibranchs that night, but as it happened, our bubbles hit the spot on the ceiling where this little slipper lobster was hanging out.  Annoyed, it skittered across the surface to escape the bubbles.  We hadn't noticed it until it moved, even though the beams from our lights had swept the area several times.

Below is another photo of the same creature.  Note the snazzy fringe along the edge of its carapace.  In case you are still scratching your head about what you are seeing, the little lobster is facing left in the photo below.  If you look very carefully you may be able to distinguish its widely spaced eyes from the rest of the mottling.

Sculptured Slipper Lobster (Parribacus antarcticus), Hawaii

The Bluespotted Ribbontail Ray

Bluespotted Ribbontail Ray (Taeniura lymma)

by B. N. Sullivan

The Bluespotted Ribbontail Ray (Taeniura lymma) is one of the smaller members of the stingray family, Dasyatidae.  We think it's also the nicest looking stingray, sporting those wonderful, eye-catching blue spots.

An Indo-Pacific species, this ray is found in the Red Sea, in coastal areas of the Indian Ocean, and around the coasts and islands of Southeast Asia.  Despite its wide distribution range, these critters are becoming scarce in some areas due to the aquarium trade:  their pretty coloration and smallish size make them attractive to keepers of saltwater aquariums.  Unfortunately, these rays do not do very well in captivity.

They are dependent on coral reef habitats for their survival.  They forage in sand patches for small crustaceans, molluscs and other invertebrates.  Naturally, their populations also have declined in areas where reefs have been degraded by development, overfishing, and so on.

The Bluespotted Ribbontail Ray pictured on this page is an adult, roughly one foot (30cm) wide.  I photographed it at Pulau Sipadan, Malaysia.

The Hawksbill Sea Turtle, a Critically Endangered Species

Hawksbill Sea Turtle (Eretmochelys imbricata)

by B. N. Sullivan

This is the Hawksbill Sea Turtle (Eretmochelys imbricata), listed as Critically Endangered by the International Union for Conservation of Nature (IUCN). This turtle species inhabits all tropical and subtropical seas around the world, but its numbers continue to decline.

The IUCN Hawksbill Turtle page notes:

extensive subpopulation declines in all major ocean basins over the last three Hawksbill generations as a result of over-exploitation of adult females and eggs at nesting beaches, degradation of nesting habitats, take of juveniles and adults in foraging areas, incidental mortality relating to marine fisheries, and degradation of marine habitats.

The IUCN estimates that "the overall decline of the species, when considered within the context of three generations, has been in excess of 80%."

While habitat degradation, trafficking in turtle eggs and meat, and incidental catch by marine fisheries threaten all sea turtle species, the Hawksbill population also has suffered due to what is known as the Tortoiseshell trade.  "Tortoiseshell" -- the material used for combs, hair ornaments, and inlays on furniture and other decorative items  -- comes not so much from tortoises, but from the carapaces of Hawksbill Turtles. Tortoiseshell collection and trade has been banned under CITES (the Convention on International Trade in Endangered Species) since 1973, yet enforcement in some parts of the world remains lax.

I photographed the Hawksbill Sea Turtle on this page at Thomas Reef in the Tiran Straits of the Red Sea.

More information about Hawksbill Sea Turtles;

• IUCN Red List: Eretmochelys imbricata
• NOAA Fisheries: Hawksbill Turtle
• Sea Turtle Conservancy: Hawksbill Sea Turtle
• National Wildlife Federation: Hawksbill Sea Turtle
• Marine Bio: Hawksbill Sea Turtles

Unspoiled Reef in the Red Sea

Unspoiled reef in the Red Sea

by B. N. Sullivan

This is the kind of scene that divers' dreams are made of: a pristine reef in a remote location.

We have been asked many times to name our favorite dive destination.  While it's difficult to choose just one location, we would have to include the Brothers Islands in the Red Sea among our top choices.  The remoteness of these two tiny specks, situated about 67 km (about 42 miles) off the eastern coast of Egypt, has helped to keep their lush reefs unspoiled.  The middle-of-nowhere location also attracts many large pelagic fishes of the sort not often seen around near-shore reefs.

The only way to get to the Brothers Islands is via a live-aboard dive boat.  It takes a full day (or overnight) at sea for the boats to reach the Brothers from coastal ports like Hurghada, Safaga or Quseir.  The voyage to the Brothers and back to the coast can be punishing due to rough seas, and dives there can be challenging due to unusually strong currents and choppy surface conditions.  But for experienced divers, the reefs along the near-vertical walls on the flanks of both seamounts (Little Brother and Big Brother) afford some of the most spectacular underwater scenery on the planet.

I photographed this dreamy, tranquil reef scene at Little Brother Island.   We think it illustrates why this location, in our experience, is a contender for Diver Heaven.

All Tucked In: Clownfish in a Carpet Anemone Mantle

Orange Skunk Clownfish (Amphiprion sandaracinos)

by B. N. Sullivan

This cute little fish really didn't want to have its picture taken.  It was hovering above the tentacles of a carpet anemone when we first spotted it, but as we approached, the fish dived under the anemone's mantle to hide.

I settled in at close range, selected the settings on my camera, and just waited. And waited. And waited some more. Finally the little clownfish peeked out (as we knew it would) and I got my shot.

The fish is an Orange Skunk Clownfish (Amphiprion sandaracinos). I'm not sure of the anemone species, but I believe it belongs to the genus Stichodactyla. I took the photo at  Pulau Mantehage, one of the islands in Bunaken National Park, a marine park in Indonesia.

A Fish with Camouflaged Eyes

Crocodile Fish (Papilloculiceps longiceps), Red Sea

by B. N. Sullivan

Many animals in the sea have evolved colors and forms that allow them to blend in with their surroundings. Some animals use their camouflage to hide from predators — and some predators use camouflage to fool their prey.

The critter in the photo above is a Crocodile Fish (Papilloculiceps longiceps), a bottom-dwelling ambush predator from the Red Sea.  The mottled coloring of this fish matches the sandy areas were it likes to lie in wait for its prey (usually other fishes).  Its body shape, including its head, is quite flat. This "low-rise" profile also makes it less noticeable to fishy passers-by.

Sometimes an animal’s eyes are the one feature that will interrupt the camouflage effect and give it away, but these images illustrate how even a critter’s eyes can be somewhat camouflaged. Take a good look at the eyes of the Crocodile Fish and notice the lappets — the small irregular fleshy flaps that partially obscure the eyeballs — a part of its disguise.

Below is a macro image of the eye of a Crocodile Fish who was nice enough to stay very still even when I came in very, very close to take the photo!  The photo is of a different individual than the one in the image at the top of the page, but it is the same species.

Macro photo of eye lappets on a Crocodile Fish

Note: A portion of this article was published previously in Photosynthesis on ScienceBlogs.com.

Living on the Wreck of the Zenobia: A Mediterranean Moray

Mediterranean Moray (Muraena helena)

by B. N. Sullivan

This is a Mediterranean Moray (Muraena helena).   We discovered this individual while diving on the Zenobia, a large shipwreck in Larnaca Bay, Cyprus. The eel was living in an algae-encrusted drain near what had been one of the big ship's lifeboat stations.

The Mediterranean Moray is known to be territorial (like many other species in its family, Muraenidae).  Thus, we were not surprised when the local dive guide who was escorting us told us that this particular Moray had been residing there for quite awhile, and usually could be seen poking its head out of the same hole on any given day.

This is a carnivorous species.  A nocturnal hunter, the Mediterranean Moray preys on fishes and crustaceans.  This eel also will scavenge dead animal carcasses.

Note:  The photo on this page was taken in 1992, during one of seven dives we made on the wreck of the Zenobia. In 2008,  I wrote about those dives in a series of articles on The Right Blue.  If you are interested, you can have a look at these posts about our dives on the Zenobia:

• Diving the Wreck of the Zenobia - Introduction
• The Wreck of the Zenobia - A Brief History
• First Dives on the Wreck of the Zenobia
• Bottom Time on the Wreck of the Zenobia
• Diving Inside the Zenobia's Parking Deck
• Final Dives on the Wreck of the Zenobia

Finally, here is a link to a recent documentary video about the Wreck of the Zenobia.  The underwater videography is good, and the wreck itself looks much the same as when we saw it years ago.  It looked to us as though many more fish now call the wreck home -- but, alas, we saw no sign of our Mediterranean Moray.

UPDATE:  Okay, we just looked at the film again, and guess what we saw: A moray! [at about 23:24 minutes].  There's no way to know if it's the same moray, or another of the same species, but in any case, the wreck of the Zenobia does still have a resident Mediterranean Moray.

A Queen Conch snail, giving us the eye

Eyes and proboscis of a Queen Conch (Strombus gigas)

by B. N. Sullivan

Conch shells, like all seashells, are created by secretions from the mantle of the snail that lives inside. This happens gradually, over the snail's lifetime.  Most people have seen empty Conch shells, yet few have seen the snails that are the natural inhabitants of those large, heavy shells.  Fewer still realize that those critters have wonderful stalked eyes.

All of the snails in the family Strombidae, to which Conchs belong, have these stalked eyes.  If you come across a live Conch shell while diving, you can see the snail's eyes for yourself if you are patient.  If you pick up the shell and turn it over, the animal inside will retract into the shell almost immediately.  Set the shell down with the glossy aperture exposed and just wait.  Eventually -- say, in five or ten minutes -- the snail will extend its eyes to look around.  If you are lucky, you also may get to see its proboscis (tubular mouth), as in the photo above.

The snail in an upended Conch shell has the ability to right itself, but to do so takes quite a bit of effort on the part of the critter.  So, if you do handle one or set it aperture side up to try and catch a glimpse of the eyes, please do return it to its natural aperture-down position before you leave it.  The photo below shows the snail's eye peeking out of the shell as it moves along the sand in its normal position.

The creature in the photos on this page is a Queen Conch (Strombus gigas), a species common to the Caribbean. I photographed this one during a night dive off the north coast of Cayman Brac.

An eye peeks out as a Queen Conch snail crawls along the sand

Moon Jelly (Aurelia aurita)

Moon Jelly (Aurelia aurita)

by B. N. Sullivan

This week we commemorate the 45th anniversary of the first moon landing  (by Apollo 11 on July 20, 1969) with a photo of a Scyphozoan known as the Moon Jelly.  Jellies of the genus Aurelia are common in coastal waters worldwide, including the Arctic.

In the photo you can see the four oral arms suspended from the body of the jelly, arranged around the critter's mouth.  Along the edge of the bell of the Moon Jelly are tiny hair-like tentacles -- not really visible in this photo.  Both the tentacles and the oral arms bear nematocysts, the stinging cells used for defense and to immobilize prey.  Moon Jellies "prey" on zooplankton.

I photographed this Moon Jelly (A. aurita)  in the Aegean Sea, just a few meters from the shore near Vouliagmeni, Greece.  This one was about a foot (30 cm) in diameter, although some nearly half again as large have been recorded.

The Spiny Puffer's Message: You can't touch this!

Spiny Balloonfish (Diodon holocanthus)

by B. N. Sullivan

You can't touch this... and you definitely can't swallow it!

That is the message that fishes in the Spiny Puffer family attempt to transmit to potential predators.  While other creatures defend themselves from predators by fleeing, or hiding, or with camouflage, members of this family (Diodontidae) inflate themselves.  In addition, evolution has armed these guys with another feature: rigid spines all over their bodies that are erected when the fish inflates.

The Spiny Puffer's spines actually are like specialized scales. When the puffer is not inflated, most of the spines lie more or less flat against the skin, but when the skin stretches during inflation, the spines go upright.

Ain't nobody gonna swallow these babies!

Puffers are not very streamlined even when they are not inflated, so they are not fast swimmers.  Once they inflate they really are ungainly.  Their little pectoral fins will flutter, but they don't attain much in the way of forward motion.  To survive, they rely entirely on making themselves look unappealing as prey.

When a Spiny Puffer is molested or feels threatened, it opens its mouth and draws sea water into its stomach.  The stomach is capable of expanding greatly -- so greatly that the stomach and its watery contents can virtually fill the whole fish, squishing the rest of its organs up against its backbone.  Its skin is stretchy, too, which also helps it to expand like a balloon.

Both fish pictured in this post are partially inflated.   Each was pottering along in a shallow reef area when we spotted them.   In each case, Jerry shined his light on the fish so that I could approach and aim the camera for a close-up of the Puffer's cute face and interesting eyes.  But these are touchy critters, and that was enough to induce them to begin to inflate, so in each instance I snapped two frames and retreated before they freaked out.

Some divers intentionally harass or even try to grab puffers, just to see them inflate.  This is quite a mean thing to do.  Remember, inflation is a defense.  If the fish begins to inflate, that means it is alarmed.  If it puffs out to its maximum, it is really scared!  This behavior may be amusing to divers, but it really stresses the poor fish.

If you see a puffer and it begins to inflate, move away from it to let it know you are not a threat.  Don't terrorize the puffers!

Spotted  Porcupinefish (Diodon hystrix)

Both of the Spiny Puffers on this page are Caribbean species.  I photographed them on two separate night dives in the Cayman Islands.  To give you an idea of their size, each of these individuals was approximately 12-14 inches (30-35 cm) in length.

Blue Snowflake Coral (Sarcothelia edmonsoni), a Hawaiian endemic

Blue Snowflake Coral (Sarcothelia edmonsoni), a Hawaiian endemic Octocoral

by B. N. Sullivan

The underwater landscape in Hawaii is not known for the presence of soft corals. There are hard, stony corals aplenty on Hawaiian reefs, but the sea plumes, colorful Nephtheid soft corals, and sea fans found on most other tropical reefs around the world are largely absent in Hawaii.

The pretty blue Octocoral pictured above is one of relatively few soft coral species that live in Hawaiian waters.  Some soft corals in Hawaii are not seen by divers because they grow at depths beyond sport diving range.  Others, like this one, are overlooked more often than not.

It is easy for a diver to swim right past a patch of Blue Snowflake coral without noticing it.  The species is what we think of as a "low-rise" coral.  The colonies form mats on the surfaces of rocks and dead coral.  From a distance, the colonies look kind of "mossy."  You have to get in close to observe the tiny flower-like polyps, but once you spot those, there is no doubt that you are looking at an Octocoral.

Blue Snowflake Coral is a Hawaiian endemic, i.e., it occurs naturally only in Hawaiian waters.  Its scientific name is Sarcothelia edmonsoni, but it was formerly classified as Anthelia edmonsoni.  (If you are searching for information about the species, you may have to look up both names).  It is a member of the Xeniidae family.

Sarcothelia edmonsoni is the primary food source for another creature endemic to Hawaii, the sea slug Marionia hawaiiensis* (formerly known as Tritonia hawaiiensis).  It makes sense -- doesn't it? -- that an endemic critter would have another endemic species as its main prey.

I photographed this example of Sarcothelia edmonsoni along the South Kona coast of Hawaii's Big Island, near the edge of Honaunau Bay.

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*I don't have a photo of Marionia hawaiiensis, so click here to see the creature on Cory Pittman and Pauline Fiene's site, Sea Slugs of Hawaii.

Fine perch for a sea turtle

Green Sea Turtle perched on the coral at Pulau Sipadan, Malaysia

by B. N. Sullivan

Sea turtles have a knack for finding comfy resting places on the reef.  Earlier this year I posted a photo of a turtle who had plopped down on a bed of soft corals to take her rest.  Here we have another Green Sea Turtle, perched this time on a table coral that jutted out from a steep bank.

We spotted this turtle at the outset of our dive, and as we passed by the same spot about an hour later on our way back to the boat, she was there again -- or still! -- surveying the scene.  She looked so comfy and at ease that we reckoned this must be her regular post.  We know from having observed the behavior of individual turtles in Hawaii over periods of years that each effectively "owns" a particular spot on the reef, returning to the same rocky shelf, or cavelet, or depression in the coral day after day over a long span of time.

To us, this turtle looked a bit like a sentry posted in a watchtower.  From the outcropping, she  had an unobstructed view of the entire bank -- left, right, up to the surface, and down into the gloomy depths -- a fine perch for a turtle.

Sea Plumes in the Caribbean

A Caribbean Sea Plume (Pseudopterogorgia sp.)

by B. N. Sullivan

In earlier posts (such as this one about the Red Sea) I have noted that underwater scenery varies a lot from one region to the next.  Fauna characteristic of a given area can provide instantly recognizable clues to the location of a photo.  For the Caribbean and adjacent tropical waters, one of those clues is the presence of Sea Plumes like the one in the photo above.

Sea Plumes can be found on patch reefs and along dropoffs throughout the Caribbean, as well as some areas of the south Florida coast, the Keys, and in the Bahamas [which are technically in the Atlantic, not the Caribbean].  They are a type of Gorgonian soft coral, in the same taxonomic Order as Sea Fans and Sea Whips.

The polyps of Sea Plumes tend to be arranged in rows along their branchlets.  The colony has a furry or fuzzy appearance when the polyps are extended, as in the photo above.  When the polyps are retracted the branchlets have a smooth, stick-like appearance.  Sea Plumes like to establish themselves in areas where there is some tidal current or other flow that facilitates feeding.  To feed, the polyps catch plankton and other nutrients that pass over them.

Sea Plumes come in an assortment of colors -- mostly greens and browns, but also purple.  The color depends on the presence or absence of zooxanthellae in their tissues.

Some species grow more than a meter tall.  The one in the photo above, which I photographed at Cayman Brac, was about a half meter tall and its branches spread nearly a meter wide.

The Yellowbar Angelfish (Pomacanthus maculosus)

Yellowbar Angelfish (Pomacanthus maculosus), Red Sea

by B. N. Sullivan 

If you dive near tropical reefs in the Indian Ocean or the Red Sea, you may encounter the Yellowbar Angelfish (Pomacanthus maculosus).  Often you will see them nibbling on a sponge,  or pecking at corals and algae-covered rocks.  In our experience, they don't seem to be fearful of divers, often swimming right up to have a look at us.  They are known to be territorial, so perhaps they approach divers to judge if they are friend or foe.

The adult of this species, pictured above, grows to a rather large size (for an angelfish!) -- up to about 20 in (50 cm).  The bright yellow patch on their flanks makes them easy to recognize.  Legend has it that the splash of yellow depicts a map of Africa.  That may be a bit of a stretch, but it accounts for the fact that an alternate common name for this species is Map Angelfish.  In any case, the exact shape of the blotch is unique to each fish, rather like a fingerprint.

The individual pictured above was photographed in the Red Sea, near Sharm el-Sheikh, Egypt.

A Splash of 'Velvia' Color on a Sipadan Reef

by B. N. Sullivan

In the days before digital photography, we shot all of our photos as transparencies (slides).  From about 1990 onward, my preferred film for use underwater was Fuji Velvia (ISO 50).  We jokingly referred to it as "Disneychrome" because it rendered such dazzling colors.  Also, it was developed using the E-6 process, available just about everywhere including on many live-aboard dive boats.  No more having to send the Kodachrome off for processing and waiting, waiting, waiting for the results.

I do not miss most aspects of film photography.  I certainly don't miss having to return to the boat or shore to change film after, say, 36 shots [you can't change film underwater!], nor do I miss having to wait until the film was developed to see if the images I captured were the ones I wanted.  But, once in awhile I get nostalgic for the incredible color saturation and fine grain that only Fuji Velvia seemed to yield.

The photo above was shot using Fuji Velvia.  The transparency was later scanned for online use.  The subject was an unusually 'fluffy' crinoid -- species unknown -- posing for us near a stand of equally fluffy-looking and very colorful Nephtheid soft corals. The location was Barracuda Point at Pulau Sipadan, Malaysia.

Why Underwater Photographers Need Rearview Mirrors

Whitetip Reef Shark sneaking up on a diver

by B. N. Sullivan

This underwater photographer was so completely engrossed in setting up his shot of some tiny creature that he was oblivious to the two sharks approaching him from behind.  The curious sharks ultimately swam right above the diver, as if to have a look at what he was doing, then continued on their way down the reef.  The diver never did see the sharks.

Lesson: While you are in the deep, it might be a good idea to look up, down, and over your shoulder from time to time -- if only to see who (or what) is looking at you!

The sharks are Whitetip Reef Sharks (Triaenodon obesus), photographed at Pulau Sipadan, off the coast of Borneo.

Stony Corals in the Red Sea

Red Sea hard corals

by B. N. Sullivan

This is one of my favorite reef photos.  It was taken in the Red Sea at an area of Ras Mohammed known as Shark Observatory Wall.  When I took the photo, it was a sunny day and the water was very clear.  I was not very deep beneath the surface, but I was positioned below the corals. I was shooting up toward the surface with a wide angle lens, using the sun as a back-light for the coral.  Pictured are several species of stony corals common to the Red Sea, of the genera Acropora and Stylophora, and some Millepora (which is actually a Hydrozoan).

Green Sea Turtle - At rest on a bed of soft corals

Green Sea Turtle (Chelonia mydas), Pulau Sipadan, Malaysia

by B. N. Sullivan

As divers, we always exercise great caution around corals so as not to damage them.  Sea turtles, on the other hand, are not always so careful.  The turtle in this photo decided to plunk herself down for a nap right in the middle of a lush stand of soft corals.  We watched her land on the coral and then wiggle a bit as if to snuggle into her chosen spot.

The turtle resting on the bed of soft corals is a Green Sea Turtle (Chelonia mudas).  She was photographed at Pulau Sipadan, Malaysia, at a dive site on the outer reef known as Staghorn Crest.

The 'Big Guns' on Bloody Bay Wall

Caribbean Brown Tube Sponge (Agelas conifera)

by B. N. Sullivan

Although they resemble cannons, these 'big guns' are sponges -- Caribbean Brown Tube Sponges (Agelas conifera) to be exact.  We found this particular cluster of sponges standing guard on Bloody Bay Wall on the north side of Little Cayman Island.  The two larger tubes were at least two feet long.

Here is another photo of Ageles conifera that we posted a few years ago.