Javier Abalos

@abalosaurus.bsky.social

323 Followers 860 Following

I cannot be reborn as a velociraptor, but I can study lizard behaviour and coloration. Close enough.

An Aplysia sea slug, also called sea hares
A young Podarcis muralis lizard doubts before crossing a crevice using a grass blade as a bridge. The first of many challenges he will face growing up!
Adult Podarcis muralis lizards rest on top a log during a mesocosm experiment.
Adult males of Lilford's wall lizard (Podarcis lilfordi) from the island of Aire, close to Menorca. Two males are facing each other on yop if a log while adopting a raised-body posture that exposes the UV-reflecting spots and acts as a threat behavioral display.
Ontogenetic changes in Podarcis muralis throat coloration. (A) Pie charts represent the proportions of juveniles showing different throat colors (UV+w = UV+white, UV−w = UV−white, oo = orange, yy = yellow, ow = orange–white, yo = yellow–orange) in September (t1; 3–4 weeks after hatching), and June–July (t2; 1 year after hatching). The three pie charts correspond to the full data set of 417 hatchlings measured at t1 (purple), the subset of 66 surviving juveniles measured as hatchlings at t1 (green), and these same juveniles measured as yearlings in t2 (yellow). (B) Reflectance spectra from the 62 surviving yearlings showing pure color morphs (solid lines and shaded area represent means ± SEM). The dashed purple line represents the average throat spectra of 417 hatchling lizards (similar to that of the 62 surviving yearlings when first measured, see central pie chart). Spectra have been normalized by subtracting the minimum reflectance of each spectrum at all wavelengths. (C) Mean and CI95 of the chromatic and achromatic distances (dS and dL respectively) between paired measurements of throat reflectance (i.e., within-individual hatchling-yearling contrasts), separated by yearling throat color. JND stands for “Just Noticeable Differences”. Two dashed lines at 1 and 3 JNDs represent two theoretical discriminability thresholds. If the confidence interval of a point includes a discriminability threshold, the two colors are not distinguishable at this threshold according to receiver cone sensitivities and relative abundance.
Ontogeny of ventral coloration in Podarcis muralis. (A) Representative photographs of ventral coloration in a hatchling lizard 2–3 weeks after hatching (left), and in four yearlings re-captured in March 2019 (7 months after hatching). SVL stands for snout to vent length in mm. (B) Young male of P. muralis showing incipient UV-blue and melanin-based black patches in the outer ventral scales (OVS). (C) UV photograph of a hatchling P. muralis lizard showing UV+white color in its ventral surface. (D) Paired UV and visible photographs of the same subadult female (< 1 year) showing UV−white in the throat and UV+white in the belly. The difference is only apparent in the UV image. Photographs in C and D were obtained with a full-spectrum camera and two filters, each transmitting light either in the visible (400–700 nm) or the near-UV (320–380 nm) range. Brighter areas in the UV image have higher UV reflectance (i.e., hatchling ventral surface and female belly).
Juvenile common wall lizard hatching from the egg.
Coloration in common wall lizard (Podarcis muralis). a) Alternative throat colours in males and females. b) Detail of UV-reflecting spots in the outer ventral scales. Extracted from Abalos et al., 2020 (https://doi.org/10.1002/ece3.6659)
Left, conventional photography of a flower. Right, photography of the same flower obtained with a full spectrum camera equipped with a filter that only transmits light in the UV waveband. Brighter (yellow) areas show higher UV reflectance. Animals with UV vision see a difference in coloration between the center of the flower and the petals that we can't see.
Contrast of a tiger against a green vegetation background when viewed by their typical prey (a; deers and other cervids) and to a human viewer (b). Extracted from Fennell et al., 2019 (https://doi.org/10.1098/rsif.2019.0183)
Wild boar mother, showing a much duller coloration than her piglets, which show a striped brown and yellow pattern.
Maltese wall lizard (Podarcis filfolensis) in the island of Filfla
Female Podarcis liolepis female showing off her iridescent dorsal coloration
Wall lizards with different colorations
A short beaked echidna in the bushy vegetation of Tasmania
A short beaked echidna in the bushy vegetation of Tasmania
A short beaked echidna among bushy vegetation in Tasmania
A short beaked echidna among the bushy vegetation in Tasmania
Crickets engaging in antennal fencing