Fluorescence update

A few weeks ago I posted about biofluorescence in fish. So when National Geographic posted the news about a fluorescing Hawksbill turtle, I was very interested. The original article can be found here. But the short version is: “Holy sh*t! Hawksbill turtles are biofluorescent! Who’d have thought?!?”

Fluorescent Hawksbill Turtle (Capture from NatGeo video)

Fluorescent Hawksbill Turtle (Capture from NatGeo video)

This just shows how much we still have to learn about the oceans in general and how new this whole fluorescence research really is. If a creature as large as a sea turtle is fluorescent and we only found out now, what else is out there to be discovered? And what does it all mean? The reason this is extra exiting, is that it’s the first instance of a marine reptile being recorded to fluoresce. The possibilities seems endless, so keep your eyes open for more fluorescence to come!

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Ornate Ghostpipefish

So far most of the critters I’ve written about were true benthic ones; Frogfishes, Scorpionfishes, Pipefishes, they all spend the vast majority of their time laying on the bottom. The next little guys are a bit different, they are (only slightly) less lazy and spend their time hovering close the bottom. May I present to you the Ornate Ghostpipefish!

Ornate Ghostpipefish (Solenostomus paradoxus)

Ornate Ghostpipefish (Solenostomus paradoxus)

The Ornate Ghostpipefish (Solenostomus paradoxus) is another one of those truly bizarre creatures you can find when you have a good look around you while diving. They look very flamboyant and ornate, but they are remarkably hard to spot. The fact that they don’t get bigger than 12cm might have something to do with that. So if you’ve never seen them before, it might take the help of a friendly diveguide to have the pleasure of seeing them.

Ghostpipefishes belong to the order (=one level up from family) of “Syngnathiformes”, which is the same order in which you’ll find seahorses and pipefishes, but also razorfishes and even trumpetfishes and cornetfishes! So all these weirdly shaped critters are related in one way or another.

Male Ornate Ghostpipefish

Male Ornate Ghostpipefish

Male Ornate Ghostpipefish (Picture by Luke Gordon)

Male Ornate Ghostpipefish (Picture by Luke Gordon)

There still is a lot of confusion about how many species of Ghostpipefish actually exist, but there seem to be at least four. For this post, I’m sticking to the best known and most flashy one. Describing an Ornate Ghostpipefish to someone who’s never seen one is interesting. Usually it goes a bit like this:  “It’s a fish that swims upside down, with the head of a seahorse, a wide fan-like tail, a pouch like a kangaroo and it has got little filaments growing all over its body….Oh, and it also changes colour, any colour you’d like. Really, it’s a thing that actually exists!!!” Luckily there are plenty of photos to prove it.

While Ghostpipefishes are closely related to seahorses, there are a few major differences. As you may or may not know, in seahorses it’s the male that gets pregnant and gives birth. Ghostpipefishes are a bit more old-fashioned and don’t want anything to do with that modern male kind of stuff. With them, it’s the female that has a brooding pouch, gets pregnant and gives birth. Although there might be a little twist…Very little is known about them, but it is believed (not proven) that all Ghostpipefishes start out as males and later change sex to become female.

Juvenile Ornate Ghostpipefish - Still partially transparant

Juvenile Ornate Ghostpipefish – Still partially transparant

There is a LOT more we don’t know about Ghostpipefishes. For example, we don’t have a clue how long they live and it’s unknown how long they float in the open ocean as larvae. It looks like these animals spent most of their lives as larvae, floating around and then only “settle” to mate, after which they supposedly die. None of this has been properly tested, as Ghostpipefishes are notoriously difficult to keep alive in aquaria, let alone breed them in captivity, making close observations or experiments to test these hypotheses very difficult.

Social group of Ornate Ghostpipefish

Social group of Ornate Ghostpipefish

If you do want to see them for yourself, or maybe you are even ambitious enough to solve these riddles in the name of science, here is where you’ll find them. They are mostly tropical species which can be found from the east coast of Africa all the way to Fiji, but they are spotted most frequently in Indonesia and Philippines. During the last months of surveying, we found the highest numbers in Dauin with Lembeh Strait a close second. They are usually found in areas with some current and always hide in larger objects such as featherstars. You can also look for them in seafans, black corals or even rubbish. Ghostpipefishes often hang out in small social groups, so if you find one have a close look around to maybe find some more.

Pair of Ornate Ghostpipefish - If you look closely, you can see the eggs in the pouch (Picture by Luke Gordon)

Pair of Ornate Ghostpipefish – If you look closely, you can see the eggs in the pouch (Picture by Luke Gordon)

Once you’ve found them, try to see if there is a female, she’ll be the one with the brooding pouch. The pouch is formed by the pelvic fins and if you are lucky, you might be able to see eggs inside it. Unlike other brooding fish species, ghostpipefishes will have eggs in all stages of development, so at the same time there might be freshly laid eggs in there and eggs that are ready to hatch. As far as I am aware no photos or videos exists of the little ones hatching (let me know if you do!). But what really interests me is what happens to the little guys after they hatch and start drifting in the water column….

Surveys: What do we actually do?

So far I have mostly been writing about muck diving, critters, dive sites, but I haven’t really explained how researching all of this works. What do we get up to when we are diving? Do we look at weird critters and think “that’s pretty cool!” or do we actually do something more?

Perks of the job: Air ajo 3, one of the survey sites

Perks of the job: Air ajo 3, one of the survey sites

First off: Yes, Luke and me very often think, talk and even shout under water about how very cool our critters are. We do however, try to get a bit more scientific than that. Since May this year we finished nearly 200 transects on 20 different sites, besides that we have also been collecting sediment samples and we took many, many pictures of the bottom of the sites we surveyed.

Running a transect

Running a transect

Surveying sites by running transects (we are actually doing “belt transects”, but that’s a technicality that’s not important now) is a way to try to tell how many fish there are in that area. The idea is to have a fixed measuring unit, so you can compare your counts to other sites. It would not make sense to just swim for a while, counting fish if you don’t know how much area you have covered. Without a measuring unit you might swim 500m in one dive, 300m on the next one and 900m in yet another one, making comparisons impossible. One way to deal with this, is by simply taking a measuring tape with you so you know how much you area you have covered. Before you do this, you have to decide how long your transects will be and how far away from the tape measure you will count fish. This way I know that with every transect, I cover an area of 50m2, and per site I investigate 500m2 of seafloor(10 transects).

Doing this on every site we investigate allows us to make comparisons. For example, at one site I found 3 Scorpionfish, but at another site I found 35 Scorpionfish. Since I used the same methods (both covered 500m2), I can conclude that there really are more Scorpionfish in one site than the other.

Benthic cover???

Benthic cover???

This obviously does not explain WHY there are more fish on one site than another. To try and explain some of the differences, we gather data on a few other things per site. Besides noting the depth we found species, we look at a few more environmental factors that might vary. The main two are benthic cover and the actual sediment. Benthic cover is just a fancy way of saying “stuff that covers the bottom”, to investigate this we take multiple photos of the bottom at each transect. Afterwards the photos get analysed to decide how much of the bottom was sand, algae, coral,…

Initial sediment drying

Initial sediment drying

Sediment sampling is a bit more intensive. First step is easy, scooping up about sand at each transect under water. Next the samples have to be dried, packed and transported to the lab. In the lab it all gets wet-sieved, dried again, and then I can start the actual analysis. By the end of this month we will have collected about 200 samples, each of which take about an hour to process (+48 hours drying time). So a lot of hours of playing with sand ahead of me, let’s just hope it results into something useful 😉

Sediment collecting

Sediment collecting