Marine Worms

There are several different phyla of marine worms, which include species such as the flatworms, roundworms, and segmented worms. Worms are found throughout the marine environment, from the ocean surface to intertidal sediments to the deep seafloor. Marine worms exhibit a variety of lifestyles: some are parasitic, some free-living; some filter feed, some are predatory; and some live in tubes, which they construct of proteins and minerals.

Day 119.2

  • Flatworms: These worms always have flattened bodies. They are very small; some are microscopic, others are macroscopic.  Flatworms glide over the bottom of the ocean using cilia for propulsion. Others can swim using muscular contractions.
  • Ribbon worm: They are the largest worms in the ocean, averaging one meter in length. They look like flat, soggy noodles which burrow in the sand or swim gently in the intertidal zone. If you happen to pick one up they will break into many small pieces and regenerate.
  • Arrowworm: Unlike other worms these worms spend entire their lives as plankton. They are often difficult to see because they are tiny and transparent even though they can grow to be as long as three centimeters. They have stiff hairs around the mouth to eat and tiny fins for swimming.
  • Segmented: The most common marine worms belong to the phylum Annelida. They are distinguished by the little rings or segments that make up their bodies. The most common marine annelids are the polychaetes.
  • Polychaetes can be divided into two categories: errant and sedentary. Errant polychaetes worms are free swimming predators. Sedentary worms live in tubes and feed on plankton and detritus. All polychaetes worms have lateral “legs” called parapodia. Parapodia are used in respiration, filter feeding and locomotion.
  • Peanut Worms:  These worms are bottom dwellers. Their 4 in. bodies are divided into two sections – the trunk and introvert. The introvert end contains sensory cells and a mouth. Peanut worms may live in the sand or use empty snail shells for a home. Others bore into rocks for shelter.
  • Roundworm: These worms live in the sediment found in the intertidal zone, but can move freely by whipping their bodies. They feed on organic debris.