Calcium Storage in Anoles

Enlarged endolymphatic glands in two A. lemurinus museum specimens

Enlarged endolymphatic glands in two A. lemurinus museum specimens

I’ve been looking through a lot of anole museum specimens lately, and I’ve noticed that many of them have pretty pronounced endolymphatic glands, which made me curious about their prevalence and function in anoles generally.

Endolymphatic glands serve as calcium reserves, and are present in many animals, including a number of reptile and amphibian clades. According to Etheridge (1959), these glands are present in anoles and a few of their close relatives (e.g. Polychrus), but not in any other Iguanians. But it looks like most of the research on their function (in reptiles) has focused on geckos. In geckos, the size of the glands has been shown to fluctuate in response to both stress and reproductive activity, supporting the idea that the stored calcium is used in egg production, both for the yolk and the shell (Brown et al. 1996, Lamb et al. 2017). However, in anoles and geckos, these glands are present in both males and females, so their function isn’t limited to providing calcium for eggs (Etheridge 1959, Bauer 1989, Lamb et al. 2017).

But I haven’t found much information on these glands in anoles. I personally haven’t noticed them in the wild, but so far I’ve found very pronounced glands in 13/66 museum specimens, and some of them are really striking (see photos)! So I’m curious to hear, how often do you other anole-ologists see these enlarged glands? Is there any other literature about their prevalence, seasonality, or function in anoles that I’ve overlooked? Seems like we might be lagging behind the gecko crowd on this topic!

Citations:

Bauer A (1989) Extracranial Endolymphatic Sacs in Eurydactylodes ( Reptilia : Gekkonidae), with Comments on Endolymphatic Function in Lizards. J Herpetol 23:172–175.

Brown SG, Jensen K, DeVerse HA (1996) The Relationship Between Calcium Gland Size, Fecunduty and Social Behavior in the Unisexual Gecks Lepidactyluse Lugubris and Hemidactylus Garnotii. Int J Comp Psychol. doi: 10.5811/westjem.2011.5.6700

Etheridge R (1959) The relationships of the anoles (Reptilia: Sauria: Iguanidae) an interpretation based on skeletal morphology.

Lamb AD, Watkins-colwell GJ, Moore JA, et al (2017) Endolymphatic Sac Use and Reproductive Activity in the Lesser Antilles Endemic Gecko Gonatodes antillensis (Gekkota: Sphaerodactylidae). Bull Peabody Museum Nat Hist 58:17–29.

 

9 thoughts on “Calcium Storage in Anoles

  1. When the endolymphatic sacs are calcified, they are easily seen in radiographs (see Etheridge [1959] for details).

  2. I have only seen that in (Hispaniolan) Anoles of the Trunk ecomorph. In Anolis distichus from Isla Catalina (photo attached), a small island in the eastern Dominican Republic with plenty of exposed limestone. And in the related Anolis brevirostris, one individual photographed by a friend in Pedernales, an area surrounded by karst.

    There were several A. distichus individuals with that condition, though did not see it in other species (e.g. A. cybotes).

  3. Weird! I have never seen them in anoles (admittedly in my experience of a limited number of species), but, like you note, they’re pretty common and obvious in many geckos, particularly Phelsuma sp. (e.g. klemmeri always have hugely pronounced calcium sacs).

  4. Hi! I have clearly seen this in both my male and female. I didn’t know what it was and was concerned that they were lymph nodes and that they were ill, but they didn’t act ill. Attached is a photo of my male from a couple of weeks ago while shedding and you can see the “lumps.” I wonder if it happens more generally in both male and female during the reproductive cycle?

  5. They may appear much more prominent in preserved specimens owing to shrinkage caused by desiccation or whatever, so perhaps not as commonly seen in live specimens, even if present.

    1. Good point, I hadn’t thought of that. But some of these are pretty huge, so it’s hard to imagine that they wouldn’t be visible in the live lizards. I’m guessing there’s a pretty big range in size, and of course only the extreme ones are visible without radiographs.

  6. So glad someone is interested in this! I pay attention to them (always reminded me of the glands in Phelsuma) whenever I’m in the field but haven’t been good about keeping track of it in my notes. Regardless, I’ve noticed that they are either far more common or more recognizable in females. I hardly ever notice them in males, which might make sense given the research on geckos you cited.

    1. Yeah, I’m definitely going to look more closely next time I’m in the field! Cool to hear that your observations match the predictions.

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