Creature Feature – Sea Moths

posted in: Cool Creatures | 1

We have some weird critters here in the waters around Malapascua Island, making it a photographers dream. But one of the weirdest of all are the sea moths which can often be found walking (yes walking!) around in pairs.

Sea Moth on Malapascua
Sea Moth by Stewart Robinson

The sea moths, or Pegasidae, are a family of fish found in shallow coastal tropical waters usually down to depths of about 6m. However we often spot them while waiting for the Mantas at 24m! They prefer bays with sea grass or seaweed with sandy or silty bottoms, and they can be found regularly on Malapascua dive sites such as Ka Osting and Bantigue.

They are sometimes also called sea robins, Pegasus or dragonfishes.

The family contains two genera and five species.

Family Pegasidae

  • Genus Eurypegasus
    • Short dragonfish, Eurypegasus draconis
    • Hawaiian seamoth, Eurypegasus papilio
  • Genus Pegasus
    • Sculptured Seamoth, Pegasus lancifer
    • Brick seamoth, Pegasus laternarius
  • Longtail seamoth, Pegasus volitans

Growing 4-15 cm in length, sea moths are distinguished by flattened bodies, the presence of large, wing-like, pectoral fins, and a body encased in thick, bony plates. Their pelvic fins are also modified, allowing them to “walk” across the sea bottom where they live. If disturbed they can move at greater speeds by beating the caudal fin.

Sea Moth on Malapascua
Sea Moth by Andrea Agarwal

Feeding

Sea moths’ jaws are highly specialised, and can form a tube-like mouth used to suck worms and other small animals from their burrows. The mouth is situated on the underside of its long, stiff, pointed snout that is made up of modified nose bones. The mouth is protrusible, i.e., it can stick out of the body. The small size of its mouth means it can only feed on very small invertebrates that live on the substrate such as amphipods, copepods, isopods, live brine and mysis shrimp, polychaetes, nematodes, and trematodes.

Reproduction

Sea moths are believed to have social behaviour and form monogamous pair bonds, which is why we often see them in pairs.  They spawn in open water near the surface, and the juveniles may float on open waters for some time before settling down in a sheltered place near the shore.

Cleaning

Sea moths can shed their skin in one piece with a rapid jump, to get rid of unwanted parasites or encrusting algae on their skin!

Dragonfish by Ken Hoppen
Sea Moth by Ken Hoppen

Defence and Camouflage

The sea moth body is encased in a carapace that also provides some protection from predators. Some species will also partially bury under the substrate surface. But the most amazing thing about them is they have the ability to change colors based on its surroundings much like the chameleon. They sports reef-tones colors, which they can change to better match the sea floor, which means they are often hard to spot unless they are moving.

That’s why we have such eagle-eyed Divemasters at TSD 😉

  1. Chris
    |

    Stewart’s Photo is AWSOME!

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