For many of us, 2020 has been a year of chaotic coifs and hiatuses from the hairdresser, and I imagine there are a few more bewhiskered faces than usual hiding behind those laptop screens. This “Movember,” let’s pay homage to the most fan-stache-tic of facial adornments (and be mindful of Movember’s mission: to raise awareness about men’s health issues) with Puget Sound’s mustachioed mud-dweller: the shovelhead worm.
Head in the sand
With their flattened, spade-shaped heads, it’s easy to see why members of the worm family Magelonidae are called the shovelhead worms. However, when a Washington Conservation Corps intern in our lab fondly referred to our common Puget Sound species, Magelona longicornis, as the “mustache worm,” the name stuck.
The furry Fu Manchu hanging down on either side of the worm’s mouth is actually a pair of long feeding appendages, or palps. The palps move across the surface of the mud, grabbing food particles with small sticky bumps called papillae. Now that is one effective crumb catcher! A shovelhead worm’s diet includes organic debris, tiny single-celled plants and animals (diatoms and forams), and invertebrate larvae…basically anything it can get its palps on.
A chin curtain that fancy is bound to be high-maintenance, and the palps do occasionally break or get nipped off by predators. If a shovelhead worm loses part or all of its “mustache,” just like a human, it can grow it back! Unlike a human (thank goodness), it can’t eat without a mustache, and the worm has to figure out alternate arrangements until the palps regenerate.
The worm’s backup plan consists of sticking its head above the surface of the sediment and gulping water. At the same time, it extends and retracts its proboscis — a tubular, tongue-like feeding structure. These movements create an inward water current that pulls food effortlessly into the worm’s mouth. Look ma — no hands!
Can you dig it?
A shovelhead worm’s proboscis is good for more than just emergency eating — it does most of the dirty work of digging and burrow-building. Shooting forward into mud loosened by side-to-side motions of the head, the muscular proboscis pulls the worm’s entire body behind it in a slow inching fashion.
Although these worms can actively move around, they depend on their mucus-lined burrows to hide in, waving their slender bodies back and forth to circulate oxygen. Above, their ‘staches comb the sea floor for snacks until the food supply runs low and they are forced to move on to greener pastures. This need to dig and burrow makes the proboscis — dare I say it — even MORE important than the mustache. Scientists speculate that magelonids prefer fine-grained, smooth sediments because a proboscis that is damaged by coarse sand or sharp rocks means immobility, and likely death.
I mustache you a question
Aside from the function of their fabulous facial foliage, not much is known about the biology of this curious worm family. Why are some species constantly on the move, while others seem to change burrows less frequently? How do they reproduce? Why do some species have mysterious pouches on their abdomens and others don’t? Researchers from Amgueddfa Cymru – National Museum Wales have catalogued many of the 70+ species described worldwide, and they've been extensively studying them to discover what makes them tick. I personally would love to know more about these fascinating creatures, and I look forward to digging deeper to see what our Puget Sound data can tell us!
Critter of the Month
Dany is a benthic taxonomist, a scientist who identifies and counts the sediment-dwelling organisms in oursamples as part of our Marine Sediment Monitoring Program. We track the numbers and types of species we see to detect changes over time and understand the health of Puget Sound.
Dany shares her discoveries by bringing us a benthic Critter of the Month. These posts will give you a peek into the life of Puget Sound’s least-known inhabitants. We’ll share details on identification, habitat, life history, and the role each critter plays in the sediment community. Can't get enough benthos? See photos from our Eyes Under Puget Sound collection on Flickr.