Here comes the sun! The golden petal worm shines like the rays of the spring sun

Eyes Under Puget Sound - Critter of the Month

Spring is in full swing, warm days are becoming more frequent than cool ones, and, everywhere we look, we see growing things in bloom. This month’s critter has its very own set of flowery petals to show off, and they shine through the dark waters of Puget Sound like the golden rays of the sun.

Top view of a shiny gold worm with a slightly fuzzy appearance on a black background. Scale bar reads, 500 um.

All that glitters… 
Text reads, Kingdom Animalia, Phylum Annelida, Class Polychaeta, Order Phyllodocida, Family Chrysopetalidae, Genus/Species Palaenotus bellis

Named for the Greek word for gold (“chrȳsós”), worms in the family Chrysopetalidae really do glitter like the precious metal. Believe it or not, that 24-karat shine is the product of a lustrous mane that we humans could only hope for. Each of the worm’s body segments has a row of flattened, petal-like hairs called paleae that overlap to form shiny golden fans. These hairs cover and protect the top of the animal’s fragile, elongated body, and also the head, which can be retracted safely underneath.

Microscopic view of portion of a worm showing the arrangement of hairs, and detail of the hairs which look like transparent, ridged paddles.

Left: The paleae of Paleanotus bellis form overlapping fans on each segment. Middle and right: Close-up views of generalized Palaenotus paleae; images from Watson 2015, Zootaxa.

Go for the gold

Not much is known about the life history of these unique worms — perhaps because they’re so tiny, maxing out at only 3 mm long. They also aren’t common animals to encounter, as they like to hide among barnacles, seaweed, sponges, and bryozoans on hard rocky bottoms or dock pilings from Western Canada to Mexico.

Perhaps we can add to the body of knowledge about the preferred habitat of Paleanotus bellis, the Puget Sound species, as we collect them occasionally during our sediment monitoring. They tend to occur in spots with coarser sediments like sand and apparently tolerate a range of depths, from the shallow subtidal zone to over 110 meters.

A furry yellow worm with orange spots running down its side is curled on a black background.

A curled Paleanotus bellis specimen. Photo by Matthieu Leray, Smithsonian Institution, from V3.boldsystems.org.

 

Gold rush

The feeding habits of golden petal worms haven’t been well-studied either. It has been suggested that they are mobile carnivores, wriggling after their prey. This assumption stems from their formidable mouthparts, which include a muscular pharynx (kind of like an esophagus that can turn inside-out) and a pair of dark-brown interlocking jaws called stylets. Specially adapted for piercing tissue, these stylet jaws point to a life of piercing and sucking the juices from their unfortunate prey. There may even be toxins involved. Good thing they are so tiny! 

Top view of a silvery worm with pinkish spots on each segment and a slight curvature to its fuzzy body, on a black background.

Paleanotus bellis. Photo by Leslie Harris, from V3.boldsystems.org.

Petal pusher 

The distinct paleae of worms in families like Chrysopetalidae make an impression — literally! Chrysopetalids are hypothesized by some paleobiologists to be similar in form to fossilized impressions dating back to the Cambrian period, unearthed during exploration of the Burgess Shale in Canada. 

The ancient worm-like creatures in these fossils also had bundles of petal-like structures in rows across their backs, but this may just be a case of convergent evolution (where unrelated species develop similar traits independently, based on their environments), rather than a case of true distant relations. Either way, the golden petal worms are thought to be very old… or should I say, “golden oldies”?

 

Critter of the Month

A SCUBA diver in wetsuit and hood waves at the camera.
Dany is a benthic taxonomist, a scientist who identifies and counts the sediment-dwelling organisms in our samples 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.