Hurricanes and Anolis lizards of the Caribbean

Leaf anole (Anolis planiceps) gripping onto a plant. Photo by Renoir Auguste

Hurricanes are a constant threat to all across the Caribbean and they are getting more severe because of climate change. Hurricanes not only have devastating effects on humans, but also animals as well. For example, the white-tailed sabrewing hummingbird was almost extirpated from Tobago after hurricane Flora passed over the island in 1963.

Some animals have shown the propensity to adapt to severe hurricane winds, allowing them to survive. One adept example can be seen in Anolis lizards or Anoles, which can be found on every Caribbean island.

Anoles are mostly small to semi-large lizards. They are found across the Caribbean and Americas and are important components of ecosystems, feeding on a variety of insects, and are food to a variety of birds and other animals. They are considered ideal organisms for studying biology, ecology, and adaptation (among other fields).

A study by Donihue et al. 2020 showed that Anoles have found a way to adapt to strong hurricane winds: by growing larger toepads! These toepads allow the small lizards to grip onto vegetation better, thus allowing them to not be blown away by strong winds. Not only are these lizards with larger toepads surviving hurricanes, for example hurricane Irma and Maria from 2017, their offspring are being born with large toepads as well (compared to other anoles not exposed to hurricanes).

It's amazing what we can learn from animals, such as anoles, about adaptation to global events. No doubt we can learn more from them, which hopefully will allow us to appreciate them more and improve our management of biodiversity conservation.

There are at least 8 types of Anoles in Trinidad and Tobago. To learn more about these Anoles found in T&T, do get yourself a copy of the field guide to the amphibians and reptiles of Trinidad and Tobago, available from the Trinidad and Tobago Field Naturalists' Club.

Why Glass Frogs have see through skin

Tobago Glass Frog (Hyalinobatrachium orientale tobagoense) seen from below - translucent. Photo by Renoir Auguste

Animals with transparent skin in nature are rare, and our understanding of the function of it is even rarer. One example of an animal with apparent transparent skin is the glass frog. They are found across Central and South America, as well as on the island of Tobago, north east of Venezuela. These frogs, as their name suggests, have skin where the organs, bones, and even eggs (in females) can be seen through their skin. However, only from their underside, and not their back (as seen in both photos in this post). Because of this, glass frogs are better defined as being translucent due to the dorsal pigmentation.

Scientists investigated whether the imperfect transparency (only the belly and not the back) acts as camouflage, and how effective it is. They found that the perceived luminance of the glass frogs changed depending on the background, which lowered detectability by predators, and increased survival, when compared to opaque (not able to see through) frogs. It also appears that the change was greatest for the legs, which surround the body at rest which hid the frogs even more, referred to as edge diffusion. No doubt this is probably why glass frogs are so difficult to find during the day when they are sleeping!

The Tobago Glass Frog shares these similar translucent features of other glass frogs across the region. To learn more about the local glass frogs in Tobago, including where to find them, check out the Field guide to the amphibians and reptiles of Trinidad and Tobago, available by the Trinidad and Tobago Field Naturalists' Club.

Tobago Glass Frog seen from above - not translucent. Photo by Renoir Auguste

Reference: Barnett et al. 2020. Imperfect transparency and camouflage in glass frogs. PNAS.