The Masked Grouper’s Many Looks

Masked Grouper juvenile, Gracila albomarginataWe are still diving in Indonesia, but now back in Internet range with time to post a few observations. One of my recent favorites is the many different looks of the Masked Grouper, Gracila albomarginata. On a dive in the Banda Sea, I noticed a small fish that I didn’t recognize. It was bright purple with lovely red margins on its anal and tailfins. Another I saw had a light, squarish spot on its side, reminiscent of the purple Square Spot Anthias, but it was shyly darting in and around a low coral head – not the behavior or habitat of an anthias – plus it also had a small dark spot near the tail. I wasn’t the only one who noticed these fish and in comparing notes, our friend Dr. Richard Smith who had also noticed the fish, suggested that it might be a young Masked Grouper. That made sense; the squarish spot and dot near the tail just like the adult, but a different color: Masked Grouper intermediate variation, Gracila albomarginata

On the next dive, our guide Yann pointed out another under a ledge, this one only about an inch and a half long:

Masked Grouper juvenile, Gracila albomarginata

Found hiding under a ledge, this juvenile was less than two inches long

Then I found a gray version, about six inches long; the same size as the purple one with the square spot and this one had the faint “mask” like the adult – don’t know what’s going on here – male? female? intermediate?Masked Grouper intermediate, Gracila albomarginata

There were plenty of full sized, fourteen to eighteen-inch adults running around. Until these dives, this was the life stage with which we were all familiar. One of the theories of why many juvenile fishes look so different from the adults is that in territorial species, the tiny, differently colored juveniles pose no threat to the much larger adults, affording them a chance to grow up without being driven away.

Masked Grouper adult, Gracila albomarginata

An adult Masked Grouper (approx. 16 inches in length)

Coming soon on Blennywatcher: photos from our Banda Sea crossing.

Dominica Grass Beds

Dominica Grass Bed with urchins

The grass bed at Champagne, one of our favorite dive sites.

This is the last in our series of posts from our recent trip to Dominica. Alternate habitats like sand flats and sea grass beds can be “hit or miss” – we might find all kinds of interesting things or we might wander around for an hour and get skunked. Either way, it is the thrill of the hunt that makes it fun. The grass bed at the site called Champagne was a winner so we ended up diving there 3 days. The Flying Gurnards we saw were some of the prettiest we’ve ever seen:

Flying Gurnard (Dactylopterus volitans) in grassbed Dominica

One of the prettiest Flying Gurnards I’ve ever seen.

A flying Flying Gurnard (Dactylopterus volitans) Dominica

A flying Flying Gurnard (Dactylopterus volitans)

One of the animals I was happy to find was the Atlantic Longarm Octopus, Macrotritopus defilippi. The first time we ever saw one was in 2000, on a black sand bottom at the other end of Dominica. We had just visited Lembeh Strait, Indonesia for the first time and had seen our first Mimic Octopus there. To our amazement, the Atlantic Longarm Octopus behaved much the same way, stretching and contorting itself into all kinds of shapes. We chronicled the encounter in the Spring 2001 issue of Ocean Realm Magazine.

Atlantic Longarm Octopus (Macrotritopus defilippi) Dominica

The very expressive Atlantic Longarmed Octopus

Our guide Tony surfaced after our first dive to tell us we should make a second dive there to see the batfish and frogfish he found while scouting in the opposite direction. The last one into the water, I trailed behind the group and ran right into a 3-inch, black, Shortnose Batfish. “Here! It’s over here,” I signaled, but Tony was insisting that I join him across the sand to see…the batfish! We ended up seeing five different individuals, including my tiny black one and Ned got this great shot of it extending its tiny lure:

Shortnose Batfish (Ogcocepahlus nasutus) Dominica

This batfish was tiny, but it knew how to wiggle its lure.

Shortnose Batfish (Ogcocepahlus nasutus) Pair Dominica

Shortnose Batfish (Ogcocepahlus nasutus) – We saw 5 different individuals in the grass

It pays to look at everything. Our friend Madelyn found this lovely nudibranch, Spurilla sp. in a clump of algae

Nudibranch, Spurilla sp. in the grass bed in Dominica

Nudibranch, Spurilla sp., in the algae

And there were lots of eels, including a Margintail Conger – a new species for many lifelists. Goldspotted eels seem to fill the niche occupied by Sharptail Eels in other parts of the Caribbean.

Margintail conger (Paraconger caudilimbatus)

Margintail conger (Paraconger caudilimbatus)

Goldspotted Snake Eel (Myrichthys ocellatus)

Goldspotted Snake Eel (Myrichthys ocellatus)

Lots of juveniles, including Queen Triggers:

Juvenile Queen Trigger (Balistes vetula) Dominica

A juvenile Queen Trigger (Balistes vetula) hides out in the grass.

And behavior…here’s a young jack, hunting with a Yellow Goatfish. As the goatfish disturbs the bottom with its barbels, the jack dashes in and snaps up tiny fishes and invertebrates:

Shadow feeding young jack with goatfish

A young jack shadow feeding with a Yellow Goatfish

I ended last week’s post with a beautiful yellow and orange frogfish, tucked into a similarly colored sponge. In the algae-covered rocks and sand, our guides found two very cryptic frogfish – no beauty contest winners here:

Frogfish Dominica

Very well camouflaged frogfish.

A big thank you to our buddy Mike Poe, for sharing some of his photos from the trip. We’re off to Indonesia, with little expectation of access to Internet service, so we’ll post as we can for the next month – watch this space.

 

Dominica Fishes – Part 2

Juvenile Queen Angelfish ( Holacanthus ciliaris) Dominica

A Juvenile Queen Angelfish ( Holacanthus ciliaris) gives Ned a quick look.

Dominica 2014 ~ Two of our recent posts have been about our visit to Dominica in the eastern Caribbean. There were too many photos for one post, so this is Dominica Fishes – Part 2. The lizardfish below is a Sand Diver, Synodus intermedius. Just after entering the water at one of our favorite Dominica reefs, Danglebens Pinnacles,  I saw Ned make a dash for the sand down at 80 feet. He had seen the Sand Diver sitting very still, with its mouth wide-open. This could only mean one thing: it was being cleaned. Fish often flee from their cleaning stations as soon as divers approach, but Ned is a master at knowing just how close he can get and he was able to capture the tiny Pederson’s Cleaning Shrimp as they worked their way around, removing parasites from the mouth and gills of the fish.Lizardfish being cleaned by shrimp - Dominica

One of my favorite finds of the trip was this juvenile Longspine Squirrelfish (Holocentrus rufus). We were making a night dive to count fish for REEF and our group, in typical surveying fashion, was spread up and down Champagne Wall. On the way back to the boat, I decided to explore the grass bed just off the reef, when a silvery/blue flash caught my eye. Wow, bright neon orange eyes with a metallic blue back – this was unlike any fish I had seen before and I had no camera and there was no diver with camera in sight and no one saw me signaling wildly for ten minutes for someone – anyone – to come take a look. Finally, Mike Poe showed up to save the day. Back at the resort, Cassandra Neal immediately called it as a juvenile Longspine Squirrelfish, based on the dorsal fin, which was not really visible to the naked eye but showed up beautifully in Mike’s photo. Dr. Ben Victor confirmed it, saying the tiny fish had likely just settled.  Juvenile Longspine Squirrelfish (Holocentrus rufus) - Dominica

Ned spotted this five-inch long juvenile Bluespotted Cornetfish (Fistularia tabacaria) as it was drifting in open water, heading for the lone gorgonian out on the sand plain. Tiny and wispy, it disappeared into the feathery gorgonian – I was hoping to see it the next day when we returned to the site, but it was either too well camouflaged or had moved on.Juvenile Bluespotted Cornetfish (Fistularia tabacaria) - Dominica diving

We didn’t see as many Yellowface Pikeblennies as we did on 2011, but we’ve learned that populations come and go and tend to be larger when the water is warmest: Yellowface Pikeblenny (Chaenopsis limbaughi) Dominica

The Mutton Hamlet (Alphestes afer) is another good sighting for fishwatchers. This is where common names can be so confusing. The Mutton Hamlet is a seabass but is not a hamlet like the ones we are usually referring to in the genus Hypoplectrus (which are also seabasses). Mutton Hamlet (Alphestes afer) - Dominica

Another fish that is more commonly seen in the eastern Caribbean is the Spotted Snake Eel (Ophichthus ophis), usually seen during the day with just their heads protruding from the sand.Blackspotted Snake Eel (Ophichthus ophis), - Dominica diving

A fish list wouldn’t be complete without frogfish. Our guides showed us quite a few but this Longlure Frogfish, perched in a colorful sponge was the prettiest. Its lure, at the end of a modified dorsal fin spine is used to attract other fishes, which the frogfish hoovers in with a very fast gulp. Longlure Frogfish (Antennarius multiocellatus) - Mike Poe

Check in with us next week when we share finds from Dominica’s grass beds. 

More Fishy Cuteness: The Signal Goby

Crabeye Goby, Signigobius biocellatus Ned DeLoach Blennywatcher.comHere is your dose of fishy cuteness: The Signal Goby, a.k.a., Crabeye Goby, a.k.a., Twinspot Goby. Not only fun to watch, this fish has some pretty curious reproductive behavior, as we learned a few years ago.  Signigobius biocellatus feeds by sand-sifting so we find them just off reefs or near shorelines in silty, nutrient-rich sand. We have seen them from Palau through Indonesia, so they aren’t really rare, but their populations are certainly not dense. Almost always found in pairs, they tend to be a bit wary, springing off quickly to their burrows if we approach too closely.

A few years ago, on a house reef dive at Tawali Resort in Papua New Guinea, I was pleased to find a busy pair that didn’t seem to be disturbed by my presence. Our friend Claire Davies, Ned and I watched for over 90 minutes as the little gobies worked as a tag team, excavating several different burrows with their mouths and rapidly fanning with their tails, pausing occasionally to scoop up a mouthful of sand to feed. My excitement at the dinner table that evening got others fired up about going back to look for them.

Signal Gobies Crabeye Goby Signigobius biocellatus

Watch the video at the end of this post to see the tag team burrow builders in action.

The next day, I led a few friends to the site where we had watched the little gobies the day before but now there was only one! I looked everywhere, but no mate – just a single Signal Goby, bouncing around feeding, as if nothing were amiss. At dinner, we speculated about the disappearance of the fish. Ned said a snapper probably ate it. Yeah, well I suppose that could have happened but this was a fully grown fish that had survived out on the sand long enough to find a mate and dig all those burrows. So if it got picked off by a snapper just as I started observing it, this was incredibly bad timing (for me and the fish). I imagined a family spat or maybe a homewrecking third party (In the Caribbean, we once observed a mated pair of Hamlets break up over a third hamlet and reunite a few days later – there are all kinds of soap operas down on the reef).

Always the optimist, I went back out the next morning to look for it again, but still found just the one. Then at lunch, Claire reported that the missing Signal Goby was back! After quizzing her carefully to make sure she had been in the same spot, I went back to see for myself and sure enough the reunited pair was  bouncing around, digging and pecking at each other. An online search turned up a paper from a 1977 study that explained the disappearance:  after the female lays eggs in a burrow, she seals the male in, releasing him periodically over the next few days to assist with burrow maintenance. Now wouldn’t it be fun to have a “burrow cam” to watch all that! We wrote about our experience in the Winter 2010 issue of Alert Diver: The Peculiar Fate of the Missing Mate and I just reloaded the accompanying video on our Blennywatcher YouTube channel: