Opisthius Richardsoni

opisthius richardsoni

Opisthius richardsoni is an intriguing riparian ground beetle native to western North America. Residing along the gravelly and muddy margins of fast-flowing cold streams, this small but highly active beetle plays an essential role as a miniature predator in shoreline ecosystems. It is frequently seen darting quickly across open sand bars during warm, sunny days. What makes this beetle particularly fascinating is its striking resemblance to tiger beetles, which is a result of convergent evolution driven by their shared diurnal hunting habits. Known for its incredible speed and keen eyesight, this beetle is a favorite among entomologists who explore pristine mountain streams, and it serves as an excellent indicator of healthy, undisturbed riparian habitats.

Habitat: Found on the gravelly, sandy, or muddy banks of clean, fast-flowing mountain streams and rivers.

Appearance

This beetle is typically 8.5 to 11 millimeters in length, featuring a slightly flattened, oval body with a dull metallic bronze-green or greyish-black sheen. Its most diagnostic features are its exceptionally large, bulging compound eyes and the distinctive rows of large, shallow, circular pits lining its elytra, which give it a rugged, dimpled texture. It possesses long, slender legs adapted for rapid sprinting, and short, thread-like antennae.

KingdomAnimaliaPhylumArthropodaClassInsectaOrderColeopteraFamilyCarabidaeGenusOpisthius

Opisthius Richardsoni

Interesting facts

Despite being classified as a ground beetle, its large eyes and sprinting behavior cause it to be frequently mistaken for a tiger beetle.

The genus Opisthius contains only this single species in North America, making it a highly unique evolutionary lineage within its subfamily.

This species is highly specialized for life on the water's edge and will immediately dive into water or hide under gravel if threatened by land predators.

Special abilities

Using its elongated legs, this beetle can sprint at remarkable speeds across uneven rocky terrain to chase down agile prey.

Equipped with disproportionately large compound eyes, it possesses a wide field of view to easily detect the movements of tiny insects and oncoming predators.

Its specialized water-repellent exoskeleton allows it to survive temporary water splashes and navigate wet, slippery streamside rocks without drowning.

Measurements & details

Length: 1 cm
Weight: 0.00005-0.00015 kg
Lifespan: 1-2 years
Top Speed: 3 km/h
Clutch Size: 20-80
Incubation: 7-14 days

Diet & Feeding

A voracious predator, it actively hunts small invertebrates on the moist soils of riverbanks.

Primary Foods

Springtails
Fly larvae
Small mites
Nematodes

Foraging Method

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Ecological connections

eaten by

American Dipper

Cinclus mexicanus

Predated upon by this specialized water bird while foraging along mountain stream edges.

hunts

Green Springtail

Isotoma viridis

Actively hunts springtails on wet mud and gravel.

eaten by

Boreal Toad

Anaxyrus boreas

Occasionally eaten by toads hunting along the damp banks of mountain streams.

Traits

No trait badges are assigned for this object yet.

Also known as

No aliases listed yet.

Collections

Collections for this object will appear here as more themes are added.

Safety

Danger

1/5 · Very low

No special safety notes yet.

Frequently Asked Questions

How to identify Opisthius Richardsoni?

The easiest way to identify Opisthius Richardsoni is to use the Snappit nature identifier app.

How long is Opisthius Richardsoni?

1 cm

How much does Opisthius Richardsoni weigh?

0.00005-0.00015 kg

How long does Opisthius Richardsoni live?

1-2 years

How fast can Opisthius Richardsoni move?

3 km/h

What does Opisthius Richardsoni eat?

A voracious predator, it actively hunts small invertebrates on the moist soils of riverbanks.

Where is Opisthius Richardsoni usually found?

Found on the gravelly, sandy, or muddy banks of clean, fast-flowing mountain streams and rivers.

How does Opisthius Richardsoni hunt?

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