The Right Blue

Stalking the wily night critters: Hinge-beak shrimps

by B. N. Sullivan

Imagine that it's just after dark. You jump off the stern of the boat into the water and descend to the reef. You switch on your light and sweep the beam left and right to get your bearings. You see little blinking red lights all over the place. What the...??

Don't be alarmed. Aliens have not landed and dispersed on the reef. What you probably are seeing are reflections from the eyes of tiny critters called Hinge-Beak Shrimps. All of the shrimps in this family have big googley eyes that reflect when a beam of artificial light is shone on them.

These creatures of the night are little guys, usually between 3 cm to 5 cm (1.25 in to 2 in) in length. They hide all day -- who knows where? At night they come out to feed, often in large numbers, but they're not easy to find then either. Oh, you definitely will see those blinking red lights I mentioned, but if you try to find the actual critter behind the pinpoint of red light you will be unsuccessful much of the time. These critters are extremely shy, so as soon as you get near -- piff! -- they're gone!

I had wanted to photograph one of these critters for years before I finally managed to do so. I succeeded in capturing the macro image you see on this page by concentrating very, very hard on where one of those red dots of light seemed to be, then switching off my light and sneaking up to the presumed spot. In this instance, the tiny red light seemed to be coming from a pencil urchin, so I assumed the shrimp was hiding among the urchin's thick spines. I knelt down very close to the urchin while Jerry shone a small light beam near to it, but not on it, giving me just barely enough light to set up the shot. I pressed the shutter release and voilà! Gotcha!

Now, about that funny name, Hinge-beak shrimp. Shrimps in this family (Rhynchocinetidae) have a beak-like rostrum that can bend. In fact, the name Rhynchocinetidae actually means 'movable beaks'. Other kinds of shrimps do not have this feature.

We first encountered these shrimps in the Caribbean Sea where the dive guides called them Red Night Shrimps. It turns out that the shrimps' bodies are mostly red, but that name referred to the red glow from their eyes at night. We have since seen species from this family almost everywhere we have dived around tropical reefs at night: Caribbean, Red Sea, Hawaii, and throughout the Indo-Pacific region. Each locale seems to have its own common name for the creatures in this family. We think the name Red Night Shrimps really suits them, so that is what we like to call them.

Green sea turtle (Chelonia mydas) at a cleaning station in Hawaii

Look what Jerry found on Google Earth!

We have mentioned cleaning stations in several of our blog posts. Here is a short video of a Hawaiian Green Sea Turtle (Chelonia mydas) being 'serviced' at a turtle cleaning station on the Big Island's Kona Coast. Visits to these cleaning stations are the turtle version of going to a beauty salon for a spa treatment. The turtle looks like she's saying, "Ahhh" -- don't you think?

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

Goatfish: Tropical bottom-dwellers

by B. N. Sullivan

Take a close look at the photo on this page, and you can understand how this fish family acquired the common name Goatfish. Members of this family (Mullidae) all sport appendages on their chins that look like very fat whiskers. As the story goes, these 'whiskers' suggest a billy-goat's beard.

Those appendages are called barbels, and they are a kind of sensory organ. They sense chemical 'smells' and a goatfish uses its barbels to help it locate a meal.

Goatfish are bottom-dwellers. They like sandy areas, where they can rummage in the sediment for tasty morsels to eat. They eat small crustaceans, worms, snails -- just about any little invertebrate they can find under the surface of the sand. Some goatfish species also eat tiny fishes; we have seen goatfish use their barbels to nudge little fishies out of their hiding places in reef crevices and then gulp them right down.

Most goatfish species live in relatively shallow water, so it is not uncommon for snorkelers to spot them. During the day, goatfish often hang out in small groups in sandy areas at the edges of coral reefs, where you might see them lying on the bottom. Most of their feeding activity takes place at night, but sometimes you might see some goatfish nosing around, looking for food during daylight hours.

Goatfish are quite adept at changing their coloration. Most assume one color pattern while at rest, and another when swimming. There are some that even sport a specific color pattern just for feeding!

The fish in the photo on this page is called Forsskal's Goatfish (Parupeneus forsskali), common in the Red Sea. It is solid-colored during the day, with a very dark stripe on each side that runs the length from its nose, through its eye, and almost to the base of its tail. At night, while the fish is feeding, the dark stripe becomes blotchy, and the body of the fish is mottled rather than solid. The photo was taken during a night dive at a reef near Safaga, Egypt. [Click on the photo to enlarge.]

In case you are wondering if these are edible fish, yes, they are. We've never eaten goatfish, but we have seen some for sale at fish markets in several countries, particularly in Asia. In fact, some of the larger goatfish species look like they could be quite meaty. If any of our readers have dined on goatfish, we would be interested to know how they tasted, so do tell us.

Invertebrates are such spineless critters!

by B. N. Sullivan

Readers of The Right Blue have been very patient while I turned my attention to 'another blog' for the month of August. (Yes, I feel a bit like I have somehow been unfaithful!) Never fear: on August 31 I ended my month-long tenure over at Photo Synthesis. So, dear readers of The Right Blue, I am all yours again.

In order to tie things up tidily, here are the links to the final two posts that I did over at Photo Synthesis:

Now I have one more thing to tell you about. There is a blog carnival called Circus of the Spineless, "A monthly celebration of Insects, Arachnids, Molluscs, Crustaceans, Worms, and most anything else that wiggles, crawls or fluttered. (Spineless = invertebrates, i.e., critters with no backbones.)

One of the articles I did for Photo Synthesis -- the one about the Bearded Fireworm -- is featured as a part of this month's Circus of the Spineless, which is hosted by Susannah Anderson at her nature blog, Wanderin' Weeta. Do go and have a look at the great collection of photos and articles about all manner of creepy crawly things over there. It's quite an education.

Thanks, Susannah, for including my creepy crawly Fireworm in this month's Circus.

And now, back to our regularly scheduled programming on The Right Blue...