Pacific Northwest Clam Identification Guide

Part of learning to clam is learning what you’ve actually got in your bucket. Different clams live in different places, dig differently, and — importantly — fall under different limits. Here’s how to tell the Pacific Northwest’s common clams apart.

The first split is the big one: razor clams vs. bay clams.

Razor clams (the surf clam)

Pacific razor clam — Siliqua patula

• Shell: Long, narrow, slightly curved; thin and glossy; golden to olive-brown. Shaped like an old straight razor.
• Size: Commonly 3–6 inches.
• Where: The surf zone of open sandy ocean beaches — Long Beach, Twin Harbors, Copalis, Mocrocks, the Clatsop beaches. Not in bays.
• Tell: If it’s long, thin, and you dug it in ocean surf, it’s a razor clam.

Everything else on this page is a bay clam — dug in the mud, sand, and gravel of protected estuaries at low tide.

Bay clams

Gaper clam (horse clam, empire clam) — Tresus capax

• Shell: Large, heavy, oval; up to ~10 inches. The neck (siphon) is so big it can’t fully pull into the shell — hence the permanent “gape.”
• Depth: Deep — 1 to 3 feet down.
• Show: A large round hole up to ~1¾ inches.
• Tell: The biggest bay clam, with a gaping shell and a huge neck. The prized siphon makes great steaks and chowder.

Cockle (basket / heart cockle) — Clinocardium nuttallii

• Shell: Round, heart-shaped from the side, with strong ribs radiating out; up to ~5 inches.
• Depth: Very shallow — surface to ~6 inches; can even “walk” along the surface.
• Tell: Round, ribbed, sitting near the surface. The easiest clam for beginners — often just a rake-and-grab.

Butter clam — Saxidomus gigantea

• Shell: Heavy, oval, with fine concentric rings; up to 4–5 inches.
• Depth: 6–14 inches.
• Show: A rectangular slot — “like a flathead screwdriver was stuck in the mud.”
• Tell: Chunky and gray-white, found in sand and gravel. Prized for chowder. Note: butter clams hold PSP toxin longer than most species, so mind closures.

Littleneck (native and Manila) — Leukoma staminea / Venerupis philippinarum

• Shell: Smallish, round to oval, with crosshatched (radiating + concentric) ribbing; 1.5–3 inches. Manila littlenecks (introduced, now dominant on many beaches) often show a purple tint near the siphon end.
• Depth: Shallow — within a few inches of the surface.
• Show: A small figure-8 shaped hole.
• Tell: The classic “steamer.” Small, round, near the surface, sweet and tender.

Softshell clam — Mya arenaria

• Shell: Thin, brittle, chalky white, oval/elongated; 3–5 inches. Breaks easily.
• Depth: 4–8 inches, in the muddier, brackish upper parts of estuaries.
• Tell: Fragile white shell, big neck, in soft mud. The East-Coast-style steamer/fried clam.

Purple varnish clam (invasive) — Nuttallia obscurata

• Shell: Oval, thin, flat, with a glossy brown-purple “varnished” coating and a purple interior; up to ~3.5 inches.
• Depth: Shallow, high in the intertidal, in very dense beds.
• Tell: That varnished purple shell, found in thick clusters. Because it’s invasive, Oregon allows a generous limit (72/day). Best purged in clean saltwater before cooking — they can be gritty.

Why ID matters for the rules

Limits are set by species. In Oregon, for example, gapers, butters, littlenecks, and cockles share a 20-clam aggregate limit (max 12 gapers), purple varnish clams get their own 72, and softshells fall under “other clams.” Some species must be kept regardless of size. Knowing what you’re holding keeps you legal. (See bay clam limits and razor clam limits.)

Where to go next

• Digging the surf clam: how to dig razor clams
• Digging the estuary clams: how to dig bay clams
• The species overview: Pacific Northwest bay clams

And whatever you’re after, ClamClock tells you when your beach is open and safe before you make the drive.