One day, I’m going to make a list of all of the cool examples of parasites that substantially alter their host’s morphology. Today is not that day. But I do have a really neat example to add to the future list: FASCINATING BORING ISOPODS.
Mangroves are salt-tolerant trees that are important sources of coastal habitat and erosion control. Many species live in, on, and amongst mangrove roots, including a cute little isopod: Sphaeroma terebrans. The mangroves probably don’t think the isopods are all that cute, though, because the isopods bore into mangrove root tips. It has long been hypothesized that this naughty boring behavior might have big effects on root growth, and a recent field experiment confirmed this suspicion. When isopods were excluded from roots using mesh cages, roots grew 2.5-19 times more than they would have without isopod-excluding cages (Davidson et al. 2016). Protected and control roots were also morphologically distinct in metrics other than total length, and you should see Figure 4 in the open access PDF for a nice visual of that.
During the field experiment, 15% of the protected roots became anchored, while 0% of the control roots became anchored. So it looks like isopods really affect the rate of formation of mangrove habitats and the structure of those habitats! That might have far-reaching impacts on the invertebrate and fish communities that rely on the mangroves.
There are many other parasites in many other habitat-forming host species around the world (e.g., corals, Acacia trees, kelp), which makes one wonder how much global habitat distributions and structure are controlled by our Parasite Overlords…or perhaps that’s just me, writing this blog post at 11:50pm.
Davidson, T. M., G. M. Ruiz, and M. E. Torchin. 2016. Boring crustaceans shape the land–sea interface in brackish Caribbean mangroves. Ecosphere 7(8):e01430. 10.1002/ecs2.1430