Valentine special: Sex on the sand

In the aftermath of valentine’s day, I figured a post about nautical naughtiness was suitable. Popular media such as romantic comedies, reality tv-shows or more dubious videos available on the internet might have you believe that a moonlit fondle on a tropical beach is the highlight of romance. They are, however, very much mistaken! Late night walks on the beach turning into passionate, steamy scenes of desire and lust are in fact the best way to discover that sex and sand really don’t mix well. No matter how hard you try, sand will get where you absolutely don’t want it to get. But for creatures that spend their entire lives on soft sediments there is no way around it. They have no choice but to deal with the gritty truth that is sex on sand. As you can imagine, this blog is not going to be a pretty story, but if you think you can handle it, here is how things go down in the muck…

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A small male frogfish (Antennarius pictus) risking his life to get closer to a larger female

Getting started with one my favourites, frogfishes, immediately proves my point on how difficult romancing is on the sand. As in humans, competition for females is fierce, but competition is made worse because frogfish are usually quite rare, so there aren’t many females around. The result is that males will often stalk a female for multiple days or even weeks, waiting until she might be ready to mate. This is a very risky strategy though. At best, the larger female will reject a male by pushing him away or swimming off. At its worst, the grumpy female might decide to eat the male! It sure would make Tinder a lot more exciting if this trend would catch on in humans. Have a look at a cannibalistic frogfish below (Video by Albert Kang).

When the female frogfish is in the mood however, the male will gently put its pectoral fin on her belly when they’re almost ready to mate. He’ll prod her until she’s ready, at which point the female swims up, partially pushed by the male, and releases her eggs. The male then releases his semen over the eggs, after which the now fertilised eggs drift off, forming a sort of raft until the young frogfish hatch. The attentive blog-reader will have noticed that frogfish also avoid the sand when mating, clever! Here is a rather explicit video of two hairy frogfish in action (video by BlueWaterLife1)

Unlike frogfish, the blue ringed octopus wastes no time on small talk or courtship. Male blue ringed octopuses just pounce upon any opportunity, inserting their hectocotylus (scientific slang for “penis-arm”) in any other blue ringed octopus they encounter. The problem is that males unfortunately can’t tell the difference between males or females. So they will try any octopus and only know if they hit the jackpot or got themselves into a rather embarrassing situation until after attempting to copulate (not unlike some drunk male tourists in dodgy bars in Thailand or the Philippines). The unfortunate males on the receiving end don’t seem to take it too badly and do not react aggressively, preferring to wait passively until the mistake becomes obvious. The females however are more feisty and tend to finish the act by “forcefully pulling the males from their body“, occasionally attacking or even killing and eating the males (is it me or am I seeing a trend here?). The actual deed takes on average 90 minutes, but I think we can all agree it hugely lacks in romanticism.

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A blue ringed octopus on the prowl. For what I don’t know, and turns out neither does he…

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Male Thorny seahorse (Hippocampus histrix) showing off its pregnant belly

Seahorses are more romantic, forming stable couples that sometimes stay together for life. The couples greet each other every morning by doing a little dance. When mating their dance gets more elaborate and ends up with both fish swimming up in the water-column and doing the act at the highest point of their dance. But then it gets a bit kinky, as it is the female who penetrates the male! She deposits her eggs in the male’s pouch, who then fertilises the eggs, gets pregnant and gives birth to baby seahorses. Shortly after giving birth the couple mates again (within as little as 30 minutes for pygmy seahorses!), and the males gets pregnant all over again. No rest for these little guys!

At least for nudibranchs life is a bit simpler, there is no such thing as a male or female nudibranch, since they are both at the same time. It is believed that being hermaphrodites (simultaneously male and female) is an adaptation to being rare and not being able to move very far during their lifetime. After all, you wouldn’t want to spend half of your life on your own, getting increasingly horny, to then finally meet a single other individual of your species and find out you can’t reproduce with them. So when nudibranchs mate, they usually get pregnant and make the other one pregnant in one go, talk about efficiency. Being efficient at mating does not mean mating is a boring occasion. Nudibranchs are some of the most deviant critters in the ocean. They occasionally indulge in mating aggregations (aka orgies),  S&M (most of their penises have backward pointing spines), mating with different species than our own (a slug’s a slug), and some species even practice protandry (adults mating with juveniles). But it gets even worse….

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Nubibranch sex: These Gymnodoris nudibranchs clearly show how both animals penetrate each other at the same time

Some species amputate their own penis after mating, mostly because pulling out is just too much effort with those backwards pointing spines. They do have spares and the amputated penis regrows, so no harm done. In what is probably one of the most bizarre cases of sex on the sand, a species of Siphopteron-slugs uses a part of its forked penis to stab its partner through the head during mating! You read that correctly, they use an adapted penis to stab each other in.the.head while having sex. Not the mouth, not any other orifice, the head, right above the eyes. As if that’s not enough, they even inject prostate fluid into the head as well. A process beautifully coined as “cephalo-traumatic secretion transfer”. Call it what you want, this stuff is a bit too kinky for my liking. Oh, and the reason why? You guessed it…we don’t know, although researchers have suggested it might change the behaviour of the receiving slug, go figure…

As you see, sex on the sand is a lot more complicated (some might argue interesting) than in more conventional places. Try to remember that during your next romantic walk on the beach.

 

 

 

 

 

 

Flamboyant Cuttlefish

It’s been a long time since I put a critter in the spotlights, so it’s time for one of my personal favourites: the Flamboyant Cuttlefish! I am definitely not the only one to like this amazing little animal, for most divers it is high in the top 10 of critters to see. With good reason as well, Flamboyant Cuttlefish are one of the most beautiful and intriguing inhabitants of sandy dive sites.

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Flamboyant Cuttlefish (Metasepia pfefferi) striking a pose

The small cephalopod many divers call “Flamboyant Cuttlefish” are in fact two species: the Flamboyant Cuttlefish (Metasepia pfefferi) and the Paintpot Cuttlefish (Metasepia tullbergi). The first one lives in Malaysia, Indonesia, Papua New Guinea and the north of Australia. The Paintpot Cuttlefish is found further north, from the Gulf of Thailand all the way up to southern Japan. Both species are classic muck dive critters, they only occur on muddy or sandy bottoms, so you will have to move away from coral reef to encounter them.

flamboyant-cuttlefish3So why does this animal deserve the effort of searching sandy plains for days on end, in the hope catching a glimpse of it? To start with (the name is a bit of a give-away) they are very flamboyant critters. We are talking yellows, pinks, blacks and whites, all at once! If that wasn’t enough, they often change their colours into “traveling waves”, even more so than normal cuttlefish or octopuses. From my experience, smaller Flamboyant Cuttlefishes have the brightest colours and make the most extravagant displays. When I write small, I do mean really small: adults do not grow much bigger than 8cm. They ideally sized Flamboyant Cuttlefish for the best colour-show  would be around 3-5 cm!

If finding an animal that size seems difficult, you might also want to consider the following. When they are not disturbed, hunting, or mating, Flamboyant Cuttlefish are anything but flamboyant. In their “standard” state, they blend in perfectly with their background, so they will be a mottled grey, brown, or black. For this reason some divers or photographers are tempted to disturb the animal to better see its colours. It is obvious that this is a bad idea, as it will stress out the cuttlefish. Be patient  instead, observe it for a while and you might even be rewarded by seeing it hunt small shrimp, lay eggs, or even mate!

Another thing that is special about them is that they do not swim, but walk across the bottom. To do so they use two of their arms and an adaptation of their mantle. They can swim, but only do so when they’re startled and over short distances. I could easily spend an entire dive watching these guys wander across the seafloor, little blobs of colour on a quest to eat as many shrimp as possible. It might be because of the awkward way they walk, but I always imagine them to be mildly grumpy animals. A bit like an old man with stiff joints who can’t walk that well, grumbling to himself about how the terrible weather…

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A juvenile Flamboyant cuttlefish (M. pfefferi) walking across the rubble

An interesting mystery surrounding these animals is whether or not they are toxic. Their colours would suggest some form of aposematic colouration, in the same way nudibranchs advertise their toxicity with bright colours. Some authors have even suggested flamboyant cuttlefish might mimic nudibranchs such as the Ocellate Phyllidia (Phyllidia ocellata). I have however, not read a single bit of conclusive evidence of this. It seems to be one of these “facts” people have assumed, written about and then it just got copied. To date there seem to be no papers out their describing whether or not Flamboyant Cuttlefish really are toxic, and which toxin they would produce. If anyone would have come across that information, I would be very grateful if you could share it with me and the rest of the world.

As is often the case with small critters, we don’t know very much about them. But that doesn’t have to stop us enjoying looking at them. Which is why I couldn’t resist adding a video of one of these guys. The title is a bit too sensational, but the footage is great, enjoy!

 

 

Blue-ringed Octopus: cuteness with a twist

I am definitely not the first person to write about the Blue-ringed Octopus, and once you’ve seen one for yourself it is quite understandable that people get excited about them. Blue-ringed Octopus are probably one of the only invertebrates you can call “cute”. With their small size, interesting behaviour and iridescent blue rings they look like something out of a cartoon. Add the intriguing fact that these animals are also one of the world’s most venomous animals, and it becomes logical that people are interested in these critters.

Blue-ringed Octopuses are several species in the genus “Hapalochlaena“, depending on which source you check, there are anything between 3 to 10 species. They are all small octopuses, with the biggest one (Hapalochlaena maculosa) growing to only 15cm (body + arms). They are found from the centre of the Indian Ocean to the west of the Pacific Ocean. While their colours might make you think they belong in similarly colourful tropical reefs, they are actually more frequently found in the temperate waters of southern Australia.

A fact that is repeated very often is just how venomous these little guys are. So I won’t spend too much time on it here, but if you want to read more about it check out this link to learn all about the technical toxic details. The short version is: if you get bitten, you’d better hope to have someone nearby who is highly skilled in CPR. One of the more fascinating effects that occur when bitten is “locked in syndrome“, where you appear to be dead, but are actually still aware of what is going on. If that and near-certain death doesn’t stop people from harassing them to get a nice picture, I don’t know what will 😉 .

The most conspicuous features of the Blue-ringed Octopus, its blue rings, are actually hardly visible for most of the time. When you find one while diving and you don’t bother it too much, they look like any other well camouflaged octopus. The blue rings are a warning signal they only show when spooked or threatened. The mechanism of how they show those rings is a really neat one. The rings are pigmented cells that are usually covered by muscles that are contracted above them. It is only when the octopus relaxes those muscles that the blue rings show. Like a blanket that’s pulled away when unveiling a work of art. For more details, check out this paper.

One of the most interesting things I could dig up about this critter is about the way they mate. It turns out that Blue-ringed Octopuses can’t tell the difference between males and females! Males will try to mate with any other Blue-ringed Octopus they encounter, pouncing (that’s the technical term, trust me) on the potential partner and inserting their hectocotylus into the mantle cavity of the partner. It’s only after they insert this modified mating arm into the other octopus, that they can tell if their partner is in fact female or not. If the partner turns out to be another male, they amicably part ways, no harm done. In case they get lucky and their partner is a female, the male clings on for a long time: usually more than 90 minutes, but sometimes to over 4 hours! As a matter of fact, it seems the male tries to hang on as long as the female allows it, only breaking contact when forcefully removed by the female. If you are interested in the love life of small octopuses, you can read the original study here.

There is a lot more to find out of the Blue-ringed Octopus, such as the very basic question “How many species are out there?”. Considering that this animal is one of the most popular critters in muck dive tourism, it is surprising how little we really know about them. For my research I mostly look at fish, though I am always on the lookout to see what the best places are to find and study other interesting species. So who knows, I might just have a closer look at them in the future.

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Photo: Maarten De Brauwer