Are yellow seahorses always seen on yellow sponges?

Andrew Trevor-Jones is a Sydney resident who has been diving for over 38 years. He's dived at ‘The Monument’ at Kurnell more than 100 times, so often in fact, that he now recognises individual seahorses.

Seahorse on yellow Seahorse on green Andrew Trevor-Jones

On 14 January 2017 Andrew saw a yellow seahorse on a yellow sponge. One would naturally think that this is all about camouflage. Two weeks later however (30 January) the same fish was holding onto a green sponge Andrew has also seen the fish on a brown sponge. He stated that “Yesterday, (1 Feb), she was back on the yellow sponge, so I think that is her preference.”

Thank you Andrew for your ongoing contribution to Australasian Fishes. Long-term observations of individual fishes by divers can really help contribute to knowledge of our fish fauna.

In closing this small post, I thought that some of you might have wondered if fishes can change colour. If so, this post on the Australian Museum website might be of interest.

Posted by markmcg markmcg, February 03, 2017 00:40

Comments

Hi Andrew, I have never seen a Pot-bellied seahorse change colour. Always yellow with black spots but they generally hang around on yellowish foliage except when I'm harassing them for a photo then they will hang out on any cloured foliage to get away from me. That's down in Port Phillip Bay, Melbourne. Ken, Brighton

Posted by ken_flan almost 5 years ago (Flag)

@markmcg FYI, I have a small video of a flutemouth changing colour that I will load onto the AusMus download site.

Posted by fiftygrit almost 5 years ago (Flag)

@fiftygrit Thank you.

Posted by markmcg almost 5 years ago (Flag)

Is there a list of Australian fish that change colour? Be nice to know which ones to keep an eye on for those of us new to it :-)

Posted by stonius almost 5 years ago (Flag)

@fiftygrit I have the video. Very cool. I'll hand it over to the AM's video guy who might be able to make a nice story out of it. If that works, I'll add another comment to this journal post with a link. Thank you.

Posted by markmcg almost 5 years ago (Flag)

@fiftygrit can you please tell me the location, depth and date?

Posted by markmcg almost 5 years ago (Flag)

@stonius Sorry, but I don't know that such a list exists. @sascha_schulz any ideas?

Posted by markmcg almost 5 years ago (Flag)

@stonius @markmcg To be honest I think the list of fish species that are NOT able to change colour would be a shorter list.

Markus, do you mean fish that change colour as they grow or change sex, between periods of resting and feeding or for breeding purposes?

Posted by sascha_schulz almost 5 years ago (Flag)

I was mostly thinking of rapid colour changes that could be observed in a single dive, or even in a single shot.

But I'm still learning, so it would be good to know, for example, how representative a single image can be of a fish that has many different colourings throughout it's lifespan. Like a morph index or something. For example, Dusky morwongs can look quite different when they're 20cm long, as opposed to 80cm. The colouring *and body shape change quite a lot. Or like the intense blue edges on the female Scalyfin (Parma victoriea) and Australian Snapper (Pagrus auratus). I've seen them quite intense, but I'm unsure if they are static or transitory colourings.

So I guess I'm interested in transient colour changes to add to the fun when diving, but I'm also interested in the longer term colour changes for fish identification *after the dive :-)

Posted by stonius almost 5 years ago (Flag)

@stonius You've hit one of the nails on the head. One of the aims of Australasian Fishes is to document colour changes throughout the life cycle. As you rightly commented there can be huge variations with growth stage and sex. As @fiftygrit said, the video he just sent to me shows very fast colour change in a flutemouth. I've watched as juvenile goatfish swim over different substrate types and very quickly change their colours to more closely match the background.

Posted by markmcg almost 5 years ago (Flag)

Hi, the scaly fins I have watched seem to have intense colour almost irridesent blue but both seem to fad as they grow larger. Goatfish seem to change colour constantly red, bluish, whitish. Red seems to be mainly when they stop & rest, hard to see also the pipefish I have seen always match the colour of the Sea grass they inhabit. Thanks Ken

Posted by ken_flan almost 5 years ago (Flag)

... and many also adopt a nighttime colouration that is different again. @ken_flan .

Posted by markmcg almost 5 years ago (Flag)

Hi Markmcg - is the video public? I'd be curious to see that. I've got one of a yellowtail emporer (Lethrinus atkinsoni) changing colour over about 20 seconds.

Hi Ken, that's exactly the sort of thing I mean. Usually when I see a goatfish I think 'cool barbells, bro' and move on. Now I'll be watching them much more closely :-)

BTW, I do evangelise a bit about this project when I'm out diving. I hope that's okay. I figure the more the merrier, right? Am I correct in thinking it's not a secret or anything. :-)

Cheers,
Markus

Posted by stonius almost 5 years ago (Flag)

@sascha_schulz The video is only about 5 seconds long but in that time the fish distinctly changes colour. It's not online yet and is 17MB so won't email it. Waiting for details from @fiftygrit before handing it over to the video guy here at AMS. I'm keen to put it up on YouTube at normal speed then slowed down .

Posted by markmcg almost 5 years ago (Flag)

@markmcg 2m depth, 12th or 13th of January, at Fairy Bower Beach. I have seen it once before on the scenic route hence knowing to change the setting on my camera to video. If you see a floating Aboriginal stick, that is it.

I like these comments.

So I am not the only one curious about the colour changes...

Fish appearance is not static and one photo is not a complete record of a fish species.

Posted by fiftygrit almost 5 years ago (Flag)

@markmcg can I naturalist be configured for vid? Seams a shame that only static images are allowed.

Posted by fiftygrit almost 5 years ago (Flag)

Maybe we (ie Mark) can setup a "Australasian Fishes" channel on Youtube and we can link the video in an observation's comments once its posted?

Posted by sascha_schulz almost 5 years ago (Flag)

@sascha_schulz @fiftygrit @stonius Thanks guys. Plenty of food for thought here! I'll mull it all over tomorrow at work and post a longer comment(s).

Posted by markmcg almost 5 years ago (Flag)

@fiftygrit thank you for the video details. I've sent those with some instructions to the video guy here at the AM. Agreed that one photo is not enough. At the moment, iNaturalist does not handle video. I've asked about this issue. More info in my next comment to @sascha_schulz @stonius

Posted by markmcg almost 5 years ago (Flag)

@stonius Please evangelise away!! The more the merrier. I'm looking at publicity options at the moment. Feel free to spread the word far and wide. :)

Posted by markmcg almost 5 years ago (Flag)

@sascha_schulz The Australasian Fishes channel on Youtube is a great idea. The only issue with that is that there would need to be an iNaturalist observation (still image) to hang the Youtube video URL off. I'll discuss your suggestion more widely. What do you think @harryrosenthal?

Posted by markmcg almost 5 years ago (Flag)

I really like the idea of an Australian Fishes channel for behavioral observations. I haven't posted that much, but already there have been a number of times where I've thought 'if only I could post a few seconds of video'.Maybe iNaturalist could allow embedding of video links in their pages that play using the youtube player?

Posted by stonius almost 5 years ago (Flag)

Good idea @stonius. I'll run that past the iNaturalist team.

Posted by markmcg almost 5 years ago (Flag)

@stonius @sascha_schulz @fiftygrit Hi guys. I've looked into the video options on iNaturalist, including the embedding option. For now it is not their priority. So, I think a new Australasian Fishes YouTube channel is not a bad idea at all. I need to run it past some people first, but if we go down that road, we can easily add a link to the video to the Australasian Fishes observation. See this for an example. https://inaturalist.nz/observations/2824260

Posted by markmcg almost 5 years ago (Flag)

Yup, well that works :-)

Posted by stonius almost 5 years ago (Flag)

Just a quick comment regarding the colour change in seahorses. Hippocampus whitei, the species in Andrew's photo, can readily change its colour to match its surroundings. When you find them in the Posidonia seagrass they are generally grey in colour, on the cauliflower soft corals in Nelson Bay they are typically white to purple and those on the sponges will often be gold or red. When I first started collecting data on whitei I used to record colour information of each individual I tagged but found it was kind of pointless as they would change colour depending on what their holdfast was. I did note that those that were yellow/gold in colour were much less likely to change colour.

How they change their colour? I have no idea on that one. But the reason why they change colour would be for camouflage.

Posted by daveharasti almost 5 years ago (Flag)

Thanks heaps @daveharasti. One more question. Do you know how quickly H. whitei can change colour? Is it a matter of minutes, hours or days? Thanks again. M

Posted by markmcg almost 5 years ago (Flag)

H. whitei can change their colour rapidly (seconds) when they perform their morning courtship dance with their partner. A dark animal can turn very pale during courtship and then at the conclusion of the courting they will return back to their primary colour. When it comes to habitat colour change, I've noticed with one of my tagged animals that a seahorse that was red in colour (living on orange sponge) turned dark grey within 3 days when it started hiding among the Dendronepthya australis softcorals. So changing colour to match their surrounds obviously can occur within days.

Posted by daveharasti almost 5 years ago (Flag)

Brilliant! Thank you @daveharasti. That's really cool. I appreciate your reply.

@fiftygrit, your video of a flutemouth changing colour will go online soon.

Posted by markmcg almost 5 years ago (Flag)

And speaking of colour change, check out the video taken by @fiftygrit on the new Australasian Fishes YouTube channel. https://www.youtube.com/watch?v=BisL-kG032E. I still need to refine the channel images etc. That will happen soon.

Posted by markmcg almost 5 years ago (Flag)

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