My penultimate week here at Wakatobi Dive Resort has already passed and less than seven days remain. If you have missed my previous blogs I have spent the last seven weeks observing and documenting the social and reproductive behaviour of pygmy seahorses for my PhD studies. There have been highs and lows during this time when I have been lucky enough to witness the birth of a new generation of Denise’s pygmies (Hippocampus denise) and unfortunately the loss of some adults, which left their exceedingly melancholy mates (obviously without anthropomorphising too much!).
With only two weeks remaining, I began a new chapter of work by starting to observe a group of six Denise’s pygmy seahorses on the House Reef. As I wrote my last blog I had just begun this task and now, a week later, am getting to know the group pretty well.
Luckily for me this sextet are on an exposed mini wall of the House Reef and a good ten-minute swim from the jetty. The currents on the House Reef do range between nonexistent (very rarely in my experience) and wild. This past week I have been subjected to a broad array of conditions but they have been just about manageable and the site is only 11 metres, so not too deep. Every evening this week I have been spending an hour with the group and observing their interactions.
The group consists of three males and three females, which are unusual in that each one is a completely different colour, like a collection of Jelly Belly beans. Usually I must spend a few days with a group before I can easily tell individuals apart by their subtle colour, size and sex differences but this group were easy straight off. The three males are smooth and red, smooth and yellow, and bumpy and red; the three females are smooth and red, bumpy and pink, and lastly smooth and yellow.
When I start studying a new group of pygmies I must measure them, sex them and as I mentioned, distinguish between individuals. I enlisted the help of dive centre manager Ben to help with the measuring since he has a steady hand to hold the ruler next to the animal whilst I take a picture. This is the least invasive method of measuring them, the alternative would be to take them off their gorgonian host but I don’t think pygmies would have the constitution to survive this! Unfortunately, the afternoon we went only one of the females was in an open part of the gorgonian coral, so we will be trying again another day before I leave.
Sexing a pygmy simply requires an extremely close-up image to be taken from underneath the abdomen of the animal. It would be easy of course if the animal didn’t measure less than 2 cm from the tip of the snout to the tip of the tail! After I finally get this image the sexes can be distinguished by the presence of a slit in males and a raised circular pore in females. I do feel a little like a peeping tom when I take these pictures it must be said!
So, my final week has just begun and I will be collecting as much data as possible on this group, conditions permitting. I am expecting some births and will be intrigued to find out which males and females are mating. The pair bonds don’t seem too strong at the moment so the pygmy soap opera will continue! Check my website, where I have been uploading new images and my blog where I also post updates.