# Sand Dollar (*Echinarachnius parma*)

> The eccentric sand dollar (Echinarachnius parma) is a flat sea urchin that burrows in North Atlantic sand, filtering plankton with spine currents. Adults reach 8 cm and are Least Concern.

- **Category:** Invertebrate
- **Conservation status (IUCN):** Least Concern
- **Range:** North Atlantic coastal sands of North America.
- **Canonical page:** https://globalanimalguide.org/animals/sand-dollar/
- **Last reviewed:** 2026-07-16

## Scientific classification

- **Kingdom:** Animalia
- **Phylum:** Echinodermata
- **Class:** Echinoidea
- **Order:** Clypeasteroida
- **Family:** Echinarachniidae
- **Genus:** Echinarachnius

## Facts at a glance

| Attribute | Value |
| --- | --- |
| Scientific name | Echinarachnius parma |
| Diet | Detritivore |
| Habitat | Sandy seabeds |
| Lifespan | 8–10 years |
| Weight | 0.02–0.05 kg |
| Top speed | up to 1 km/h |
| Conservation status | Least Concern (IUCN) |

## Flat urchin under the sand

A rigid test with a five-petal flower pattern on top hides a skirt of spines that move food toward the mouth on the underside. Live animals are purple, not white like beach shells.

## Plankton from sediment flows

Spines create currents that deliver diatoms and detritus to mouth grooves. Burrowing keeps the animal just below the sand surface.

## North Atlantic coastal sands

Echinarachnius parma lives from Labrador to Massachusetts on subtidal and low-tide sands. Dense beds can cover hectares offshore.

## Beachcombing versus live beds

Least Concern with extensive habitat. Bleached tests wash ashore after storms; collecting live dollars from shallow beds can locally thin populations.

## Frequently asked questions

### Are sand dollars alive when white?

White discs are usually dead tests; live sand dollars are purple and covered in tiny spines.

### What is the flower on a sand dollar?

A five-part petal pattern where tube feet and respiratory pores align on the upper surface.

### How do sand dollars eat?

Spine currents pass sand grains to mouth grooves that extract organic film and plankton.

### Where are eccentric sand dollars found?

North Atlantic sandy seabeds from Canada to New England.

### Are sand dollars related to sea urchins?

Yes — they are flattened irregular echinoids in the same phylum.

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Source: Global Animal Guide (https://globalanimalguide.org/animals/sand-dollar/). Licensed CC BY-NC 4.0 — free for non-commercial reuse with attribution.