San Diego Horned Lizard

Fascinating facts about the San Diego Horned Lizard

• A 1839 description by John Edward Gray gave this lizard its name, honoring Henri Blainville, and modern genetics in 2006 and 2009 proved it deserved its own species label again. It shows how DNA can rewrite centuries-old taxonomy.
• These lizards can be found from sea level at 10 m (33 ft) up to 2,130 m (6,990 ft).
• Adult bodies measure just 2.5–4.5 in (6.4–11.4 cm) from snout to the base of the tail, yet females grow larger than males and males sport bigger horn bases on their tails, a clear case of sexual dimorphism in a tiny reptile.
• When threatened, they first freeze to match the soil’s color, then may cover themselves in sand, hiss, bite, or even squirt blood from their eyes – a cascade of defenses packed into a creature the size of a hand.
• From early March to June females lay 6–21 eggs, which hatch a few months later in August–September; over a century, over 115,000 of their relatives were killed for souvenirs, highlighting how human demand once drove a massive decline.

At a glance

About the San Diego Horned Lizard

The San Diego horned lizard (Phrynosoma blainvillii) is a flat-bodied marvel of the southern California dunes and the low-vegetation slopes of northern Baja California. Adults measure just 2.5–4.5 in (6.4–11.4 cm) from snout to the base of the tail, their skin a chameleon of reds, browns, yellows or grays punctuated by black spots that mirror the prevailing soil color. Long, spiky horns crown the top and sides of the head, while smaller spikes armor the back, tail and limbs; males sport larger tail-base horns and conspicuous hind-leg pores, whereas females grow slightly larger overall. These lizards linger at elevations from 10 m (33 ft) at the El Segundo Dunes to 2,130 m (6,990 ft) in Tahquitz Meadow, favoring sandy, sparsely vegetated terrain near ant hills where they can blend perfectly into the ground, a first line of defense against predators ranging from badgers to northern Pacific rattlesnakes. When stillness fails, they may burrow, hiss, bite, or even launch a spray of blood from their eyes, a startling last resort that has fascinated herpetologists for decades. Their diet is dominated by harvester ants, whose dry-habitat preference ties the lizard’s fortunes to the health of arid ecosystems; they also supplement with spiders, beetles, termites and other insects, making them both predator and indicator of insect community balance.

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