Growing up

Growing up isn’t always easy, going from the playful life of a child to become a (seemingly) functional adult takes blood, sweat and tears. Anyone reading this blog who longingly remembers the awkward changes your body goes through puberty, please feel free to share in comments below whether it was the pimples, the voice changes, gangly limbs or any other similar affliction you’d like to get back in your life. I am fairly confident the comment section won’t be overly populated. If you think growing up was hard for you or any other human, take some time to consider how much more extreme becoming an adult is for fish.

As you or may not know, most fish start their life as transparent larvae, floating through the blue. Once they are large enough to become proper fish, they “settle” on the reef. This settling is the first big growing up fish have to do.  Forget about years to grow from a baby into a teenager. Typically within less than 2 days, the freshly arrived larvae change colour and massively grow in size. If you think changing colour and doubling in size within a month isn’t hard enough as a childhood, consider the following. Over 50% of baby fish arriving on the reef get eaten within the first two days of arriving on the reef! Talk about a bad first day at school…

Childhood might be the most dangerous time for fish, but that doesn’t mean puberty is any easier. While we humans complain about acne and high pitched voices, fish have got other things to cope with. Many fish change colour again as they become adults, which is a minor nuisance compared to the fact that some radically change shape. Good examples are batfishes, which start by looking like leaves or flatworms to then turn into a relatively boring plate-looking fish.

Shapeshifting is peanuts compared to a process many fish have go through during puberty: sex change. Many fishes are born as one sex, but will turn into the opposite sex as they grow up. The best known example are clownfishes, which are all born as a male, but turn into females later in life. Including this process would have made “Finding Nemo” a much more interesting film in my humble opinion. Other species, such as parrotfishes and wrasses are born as females, but then turn into males as they grow up. While surprising to most people, the whole sex change thing is actually very common in the ocean.

Part of growing up in humans is learning to appreciate different kinds of food: whether it’s vegetables, olives or alcohol, children like different things than adults. The same goes for many fish species. Frogfishes for example start by mostly eating small shrimp, and then evolve a more delicate palate including fish like seahorses, lionfish, or pretty much any other fish that fits in their mouth. Interestingly, for frogfish growing up can mean that you start of as prey for a fish, but turn into a predator for that same fish once you’re big enough. Conclusion: growing up can be difficult for any animal, but some have it worse than others.

Critter getaway in Bangka

Mangrove view

Mangroves at Bangka Island

At the moment I am back in Lembeh Strait for what will be the last visit to Indonesia during my PhD. So I am making the most of it, enjoying every moment and taking time to visit friends spread out across the archipelago. A few days ago I went to Bangka Island to visit Sophie and Simon, who own Nomad Divers, a very pleasant small dive resort. I wrote about Bangka before, so check it out here if you want to know what the island is all about.

I enjoyed a few very relaxed days, playing (and losing ) board games, teaching their kids how to behave badly and philosophising about science while enjoying gin-tonics. But I also got to appreciate the abundant critters that live in the mangroves and jungle of Bangka Island. Those few days of not working (not a single dive done and no computer in sight), and just enjoying nature reminded me why I fell in love with the tropics in the first place. The beauty of Indonesia (and much of the tropics by extension) is that there is so much wildlife all around you, as long as you just keep your eyes open…or just get plain lucky.

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Tarsier in the ceiling! I never realised how long their tails were…

On my first night, while we were catching up and sharing stories about science hobbits, a small tarsier decided to have his dinner in the restaurant. These small primates are rare and vulnerable to extinction, they are only active at night and are usually very shy. If you want to see them in the wild, your best bet is to find yourself a good guide who knows where they roost during the day, so you can see them waking up and moving out to hunt when night falls. Just seeing one is great, having one sitting just above you, while eating a gecko is dumb luck and freaking amazing. For Sophie and Simon, this was a first in 4 years on Bangka!

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Nomnomnom. Tarsier (Tarsius Tarsier) eating a gecko (Hemidactylus frenatus) in Bangka Island

There was plenty to see by day as well. I had a great time wandering through the mangroves, looking around for interesting crittersAs you may or may not know, mangroves are important nursery areas for all kind of fish, so it was no surprise to see lots of baby snappers, damsels and other small fish darting around in the shallows. But there was a lot more, loads of mudskippers (skipping around in the mud, as they do), kingfishers in the trees, and the always busy fiddler crabs in the intertidal zone.

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Two male fiddler crabs facing off

Fiddler crabs are colourful little crabs, and are named for the males’ disproportionally large claw. One claw is small and used like any other crab uses its claws, the huge claw is used to show off (what did you expect?). The males wave their big claw around to get the attention of females, and to ward of other males encroaching on their territory. If you  ever find yourself in a mangrove with plenty of time on your hands, I can highly advise watching these little guys at work for a while, it’s pretty captivating and highly entertaining.

While I didn’t go into the jungle, there were plenty of little lizards to spot while strolling along the beach or heading to my room. Apparently, there are quite a few snakes to find in the jungle, and legend has it there’s even deer around, maybe I’ll have to bring shoes next time and go have a look.  If mangroves or jungle or jungle trekking aren’t your thing, you can always just chill out, have a beer and watch the geckos on the wall eating bugs or fighting each other. The tropics really are accommodating for any life style 😉

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Sophie and Max enjoying the ocean view