Every Seashell Has a Story: Hawaiian Stromb, a Very Rare Find

by B. N. Sullivan

Over the years we have become quite adept at finding shells underwater, but some species that we wanted for our collection were elusive for a long time. There were some we had seen in books or displays that we just never came across in the ocean. In other cases we had found the shell, sometimes on numerous occasions, but only ones that still had the critter living inside.

As I mentioned in an earlier post about shell collecting and diving, we do not take live shells that we find in the ocean, so we are especially delighted when we come across an uncommon or particularly beautiful shell that also happens to be empty.  In the previous post, we told the story of finding an Arabian Cowrie in the Red Sea.  In this post and the next, we'll tell the stories of a few more very special seashell finds.

The shell on this page is a Hawaiian Stromb (Strombus vomer hawaiensis),  a very rare Stromb subspecies endemic to Hawaii.   [Click on the photos for a larger view.]  Not only does it exist only in Hawaiian waters, the Hawaiian Stromb only dwells at depths below 25 meters (more than 80 ft), so the likelihood of finding it on a beach is nil, and snorkelers will never get to see it in the water, either.

The find was quite accidental: we weren't even looking for shells at the time.  We were doing a deep dive -- on a mission to photograph some cerianthid tube anemones that lived on a sand flat at Puako at a depth of about 40 meters (around 130 ft) and below.  Not wanting to rack up any more decompression time than we had planned and prepared for, we had descended quickly to the sand flat, and we were hustling to the spot where we knew the anemones lived.

The surface of that particular sand flat is relatively barren terrain, with very few rocks or other features -- just hard-packed sand and mud, gently sloping into the deep for as far as the eye can see.  For that reason, things that stick up out of the sand -- even small things like the cerianthids we were there to photograph -- are relatively easy to spot.  In this instance, what Jerry spotted as he swam along was the pointy tip of the Hawaiian Stromb shell protruding from  the sand.

As Jerry tells it, he recognized immediately that it was a piece of shell, but he figured it probably was a broken shell.  He dug it up, curious to see what kind of shell it might be, way out there in the middle of nowhere.  I watched him uncover what turned out to be a whole shell, not a fragment.  

When Jerry picked it up and brushed the sand away with his glove, I heard him shriek and saw his eyes widen behind the faceplate of his dive mask.  He held out the shell to me, and it was my turn to shriek when I realized what species it was.  The aperature of the shell was packed with sand, indicating that there was no animal inside.  What an exciting find!

This Hawaiian Stromb was a bit crusty from having been buried in the sand for who knows how long, but it cleaned up very nicely.  Our specimen is 7 cm (2.8 in) long.  It has become one of the greatest treasures in our seashell collection.

More seashell stories to come, after Wordless/Watery Wednesday...

Every Seashell Has a Story: The Arabian Cowrie

by B. N. Sullivan

Here's a special cowrie shell from our collection. The shell pictured at right is an Arabian Cowrie (Cypraea arabica). Jerry found this one in the Red Sea many years ago, and it is the only one we've ever seen, except in pictures.

I had to tell about this one today, since I'm writing this on Easter.  As it happened, we had gone on a dive trip to the Red Sea over the Spring holidays one year, and Jerry found this shell on Easter Sunday. We always joked that the Easter Bunny must have put this egg-shaped cowrie shell there for him to find that morning.

As cowrie shells go, this is a fairly large species.  The Arabian Cowrie shell pictured here is 6.5 cm (about 2.5 in) long.

The first photo shows a dorsal view of the shell.  Below are two more views of the same shell, so you can see its interesting markings.  First is a side view:

And here is what the base of the shell looks like:

Here is a link to a photo of a live Arabian Cowrie on Wikipedia. You can see the pale colored mantle of the snail that manufactures the shell and lives inside.  There was no snail inside the Arabian Cowrie shell that Jerry found.

Scarlet Hermit Crab from the Caribbean

What: Scarlet Hermit Crab (Paguristes cadenati).

Also known as the Red Reef Hermit Crab.

Where: I took this macro photo of the Scarlet Hermit Crab
while diving along the north shore of Cayman Brac, Cayman Islands.

Click on the photo to enlarge.

Conus striatus - A fish-eating cone shell

by B. N. Sullivan

In a recent post, we introduced our readers to Cone Shells, and the snails that make those shells and live in them.  We mentioned that the Cone Shell snails  have a venomous sting, making them potentially dangerous to handle when they are alive.  

Unlike some other mollusks, which eat algae, the animals that inhabit Cone Shells are carnivorous , and they use their venom, which is a neurotoxin, to immobilize or kill their prey.  Some Cone Shell snails eat other mollusks, while others eat marine worms.  A few Cone Shell species, like the one on this page, actually eat fish!

This is the Striated Cone (Conus striatus), a relatively large Cone Shell species.  The one pictured here is from our shell collection.  We found it in a sandy patch at a depth of about 6 meters (20 ft) off the coast of Puako, Hawaii.  It is  10.4 cm in length (about 4.25 in).  The Striated Cone is uncommon -- that is, it is not abundant in most locations.  At the same time, though, it is widely distributed.  It can be found in many different locations around the Indo-Pacific region, from the Red Sea all the way to Hawaii.

The Striated Cone is one of the Cone Shell species considered to be potentially dangerous to humans.  For one thing, its venom is among the most potent.  For another, the snail is amazingly flexible and agile.  Its siphon and proboscis (where the stinging radula teeth are located)  can be extended nearly the length of its shell.  Thus, even if you are careful to hold a live Striated Cone Shell by the widest end, it still may be possible for it to sting you.

The Striated Cone snail hunts primarily at night.  A wily predator, its method is to sneak up on a  small fish that is 'sleeping' on the bottom and sting it, injecting it with venom.  The neurotoxic venom paralyzes the little fishy.  Once the prey is thus immobilized, the snail literally engulfs it.

You might imagine that it would take quite awhile for a snail to engulf a fish.  In fact, the snail's proboscis (mouth) expands and it hoovers in the prey in a remarkably short time, swallowing it whole.

Don't believe me?  Have a look at this video of  Striated Cone Shell snail attacking and consuming a little fish: .

If the video does not play or display properly above, click here to view it on YouTube.

---

NOTE: This post was included in the Carnival of the Blue 23 over at Deep Sea News. (Thanks, Kevin.) We invite all of our readers to drop by the Carnival for more wonderful articles about the sea and its fascinating inhabitants.