Miniature Melo – Micromelo undatus

Miniature Melo, also known as Polka-Dot Bubble Shell or Wavy Bubble Snail is a species in the class of the Gastropoda and thus belongs to the phylum of the Mollusca. Micromelo undatus was described for the first time in 1792 by Bruguière and is also referred to as Micromelo undata or Micromelo guamensis in many sources. The correct scientific name, however, is Micromelo undatus.


The Miniature Melo has a very flat body, which is curved both in front and behind the housing.

The base colour is milky white to transparent with white spots spreading all over the body. In addition, its edge is almost rainbow-coloured

The housing is also white with red to brown, odd lines.

Light colour variations can occur in different regions.

Micromelo undatus reaches a maximum length of 4cm.

Possible Confusion

In addition to the Polka-Dot Bubble Shell, there is also the Brown Striped Paper Bubble in the Canaries. In contrast to Micromelo undatus, Hydatina physis has a reddish to brown body with a bright blue shining edge and no dots. Furthermore, their housing is light brown with dark brown stripes.

Miniature Melo Polka-Dot Bubble Shell Wavy Snail Micromelo undatus Micromelo guamensis gastropoda mollusca species canary islands diving confusion
Miniature Melo – Micromelo undatus

Habitat and Distribution

Miniature Melo is found in shallow water, on sandy or rocky ground, preferring places with algae growth. They are found from a few centimeters, such as tide pools, to about 10 m depth. In rare cases it is also sighted more deeply.

When diving in the Canaries you can observe Micromelo undatus very rarely. But if you hike along the coast you can be more lucky to discover them in a rockpools.

In addition, its distribution area extends in the eastern Atlantic from the Canary Islands, via Cape Verde, Ascension to South Africa.

In the western Atlantic you can find Miniature Melo from the Bermudas, via Florida, the Caribbean, the Gulf of Mexico, Panama, Costa Rica to Brazil.

There are also sightings in Australia, New Zealand, Japan, Thailand, Mozambique and Hawaii. They are probably found in tropical and subtropical regions worldwide.


The Miniature Melo feeds on polychaete worms. It stores their toxins in their tissues, in order to protect themselves against predators.

It is both day- and night-active. Although they can withdraw into their housing, they do so very rarely.

The housing of Micromelo undatus fluoresces under blue light extremely red while the body does green.