Ahoy Halobates! (Oceanic Water Skaters)

This week we are looking into the only bugs to make their home on the open ocean! How do they do it? Some things we know for sure, while others still remain a mystery... 

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This week's artists: HM Surf, Richard Smithson, and no one's perfect. 

 

Transcript: 

 

Welcome to episode 36 of Insects for Fun! This week we are looking into a group of bugs that made their home in the sea and it’s pretty interesting… 

 

Our journey today takes place out on the open ocean. The waters are calm and we’re miles away from any shoreline. Finally, a place where no bugs can reach me is what you think until you notice something small skating on the surface... meet the oceanic water strider known as halobates. This genus of water strider consists of around 40 species but  5 have evolved to live out on open waters completely independent from land, and these 5 can be found in approximately 50% of the open oceans around the world, but are predominately found in warmer waters within the pacific and indian ocean. There is one species found within the Atlantic but its range is limited near the equator. 

 

The genus halobates belongs to the insect family gerridae which are commonly referred to as (insert stupid music) water skaters, water skeeters, water scooters, water skimmers, water bugs, pond skaters, and or water skippers. Now there should be no one who doesn’t have an idea as to what I’m talking about (I hope). I’ll have a separate episode covering the freshwater variety but halobates were too interesting to pass up so easily. 

 

You might be asking yourself (Patrick Star: whats so great about) 

And I’m gonna tell you right now. Halobates are the only group of bugs to successfully live in the open seas away from land for the entirety of their lives. 

 

Water striders are true bugs which means they don’t have a larval stage, and Halobates are no exception. These bugs reproduce on the open sea and lay their eggs on floating debris. What’s interesting is that because sometimes there is so little floating debris, one piece can be used over and over by many different females with eggs literally layered on top of each other. 

In fact, an empty milk jug was found floating off the coast of Costa Rica and had around 70,000 eggs consisting of 15 layers. That’s insane! The eggs are quite small though being less than 1mm and shaped like a grain of rice. 

 

These bugs go through 5 molts before reaching the adult stage and have no known seasonality. They do prefer warmer waters though which speeds up their growing time. The eggs of these guys usually hatch within 10 days and then it takes another week or two for each molt until reaching adulthood.

 

Halobates like other bugs are fluid feeders which means they live off sucking up nutritious liquids from other marine animals including each other when the going gets tough. As for the major food sources we aren’t sure, but they have been recorded eating zooplankton, dead jellyfish, fish eggs, and other floating organic material. These oceanic bugs can also store triglycerides or waxy fat as reserves, which is not something the coastal variety does and this helps buffer them when food is scarce. The coastal halobates have a much easier time getting food because they prey upon bugs that fall into the waters from land, and these ones also lay their eggs on rocks and other natural structures that hug the water’s edge. 

 

Both varieties have bodies that are half the length of your traditional freshwater skaters but their legs are around the same length. This actually helps with skating across the ocean with greater speed and gives them a really good jumping height. These bugs also have very fine hairs shaped like mushrooms which trap air and act as a life vest when the bugs get pushed underwater. They can also use this trapped air as a safety reserve for breathing if they really need it. You might be picturing the bugs grabbing bubbles of air but it's important to note that bugs do not have lungs and they can simply absorb oxygen through their bodies, which makes having fine oxygen-holding hairs really convenient. Another nice adaption would be the ability to produce a waxy material that they coat all over themselves to make them even more hydrophobic. Apparently, these bugs are always grooming themselves when not moving and applying this waxy coat to their bodies which keeps them able to effortlessly skate across the open ocean. They almost hover from their hydrophobic properties with as little as 5% of their legs touching the surface of the water, and rain or waves can’t wet them down either. 

Something I found interesting about the open ocean species is that because they aren’t tethered to any form of land they’re always roaming and changing locations which makes them difficult to track on the open sea. Some days you might see thousands and the next day they’re gone. It reminds me of the mass outbreak phenomenon in Pokemon. 

 

The predators of these bugs seem to be sea birds, turtles, and some fish species but sea birds were definitely the main predator, especially small sea birds which feed by skimming the surface. One sea bird in particular might actually be targeting the bugs and that would be the blue-gray noddy with one bird having over 330 Halobates found within a regurgitated sample. 

 

Much is still left to be known about these bugs because they don’t seem to do so hot in captivity… It’s currently theorized that these bugs must need some kind of surface film that can’t be reproduced in a lab environment because they will eat fruit flies but that doesn’t seem to keep them going.