What lives out there in Seattle’s underwater landscape? That’s been the question of undergraduate interns in the Sebens Lab over the last 2 months, as they’ve analyzed photos from our recent benthic surveys.
This work was no small undertaking. It required learning hundreds of new species and species codes, and spending many many hours zooming in and out of digital photos to identify invertebrates and algae, and quantify their relative abundance on photographed surface. The curious critters they’ve encountered at times seem stranger than fiction and offer a window into Seattle’s vibrant, underwater world. Here is a compilation of their favorite finds of the quarter:
Balanus nubilis Most people wouldn’t call barnacles interesting, and truth be told, I can understand why. Barnacles aren’t exactly the most thrilling things in the ocean; they aren’t as dangerous as sharks, they aren’t as beautiful as angelfish, but just because they aren’t as flashy as their mobile compatriots doesn’t mean they are any less interesting. In particular, the Giant Acorn Barnacle, Balanus nubilis, is an intriguing creature. Growing up to approximately six inches in diameter and twelve inches in height, the B. nubilis is a filter feeder related to shrimp, and has the largest known muscle fibers in the animal kingdom. Also, the “glue” that these, and other, barnacles produce cannot be dissolved by either acidic or alkaline solutions. This has piqued the interest of some researches in the medical field, particularly dentists, in hopes of developing new medical adhesives. Giant Acorn Barnacles also provide important habitat even after they die. The shells of dead acorn barnacles sometimes form reef like structures and can act as nurseries for small fish. So although barnacles aren’t the supermodels of the ocean, they are important parts of the ecosystem and are worthy of study. – Christopher Scott Mowers (Class of 2018) 
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Cryptochiton stelleri Cryptochiton stelleri, also known as the Gumboot Chiton or the “Wandering Meatloaf,” is the largest species of chiton. It lives 20-40 years, weighs up to 4.4 pounds, and grows up to 14 inches long, and is found throughout the coast of the northern Pacific Ocean. The Gumboot Chiton has armored plates along its back, which help it bend and attach to curved surfaces. It is red because approximately 20 species of red algae live on it and because red algae makes up much of the gumboot chiton’s diet. Its tongue-like radula, used for scraping algae off rocks, has teeth tipped with magnetite, a magnetic mineral! One defense mechanism used by the gumboot chiton, as well as other chiton species, is to curl up so that its soft underside is protected from predators. Because of this, chitons are sometimes called “sea cradles”. An interesting fact is that about 25% of Gumboot Chitons have small segmented worms living on them, near their gills. These worms help clean the gills by eating material found there. – Maia Tian Sebek (Class of 2015) 
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Metridium farcimen Metridium farcimen is a species of sea anemone that is more commonly known as the Giant Plumose Anemone. It is native to the west coast of the United States and Canada. Metridium has enormous plumes and striking white, red or reddish-brown coloration that makes it impossible to miss. Large Metridium farcimen are also known to drive away other organisms and capture prey with its large tentacles. Additionally this particular species is able to reproduce sexually and asexually, through pedal laceration, leading to dense populations of the anemones. These organisms can survive for centuries. One specimen in particular lived for more than one hundred years in captivity before human error lead to its death. This species is an enormous, highly adapted filter feeder that dominates the substrate when present. – Jack Berrigan (Class of 2019)
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Parastichopus californicus Parastichopus californicus is a large sea cucumber that can be up to 50 cm in length and about 5 cm wide, with large cone-shaped pseudo spines, and tube feet on the underside for movement. Their body is soft and cylindrically shaped, with reddish-brown to yellowish, leathery skin and an endoskeleton just below the skin. They feed upon organic detritus and other small organisms by eating bottom sediments, and pooping out sand. Occasionally, they will position themselves in a current where they can use their tentacles to catch food (such as plankton) the floats by. Typically found in the low intertidal zone down to about 90 m depth (although occasionally as far down as 250 m), they are generally loners that are active at night. A few interesting things about P. californicus is that they have the ability to regenerate all parts of their body, similar to their relatives, the starfish. When threatened, they can expel all the contents of their stomach (instantaneous poop!) or a sticky white substance that confuses predators. They are a commercially fished species that is popular in Asian markets in the United States and overseas, which has led some areas to be overfished. – Dejah L. Sanchez (Class of 2015) 
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Pugettia producta Pugettia producta, the Northern Kelp Crab, is a ubiquitous feature anywhere kelp grows. It does not decorate it’s carapace to the same extent that other majid crabs do. There is speculation that when it does attach items to it’s carapace, it is doing so to eat them later. It is omnivorous, but mainly feasts on algae–only when this food source is scarce will it resort to a eating barnacles, mussels, hydroids, or bryzoans. P. producta is at times parasitized by the barnacle, Heterosaccus californicus, which modifies their behavior and physiology. The crab becomes sluggish, and during their next molt, the barnacle pushes it’s reproductive sack through the crab’s abdomen. The crab’s gonads are damaged severely if not destroyed. In some cases, male kelp crabs exhibit female morphology after being parasitized, including carapace and claw modifications, and even production of eggs in addition to sperm. – Ian McQuillen (Class of 2015) 
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Serpulid worms The rocky subtidal substrate lining the bottoms of our waters is teeming with life. My personal favorite creatures are the serpulid worms. These suspension feeders bind to solid substrate and extend their beautifully patterned feathers in order to sift nutrients floating through the water around them. If startled, they quickly retreat into their shell like home. If enough of the worms live together, they can form a cool, reef-like structure. As urban structures are being developed closer and closer to the shoreline, we disrupt their fragile habitats. They are definitely small and easy to miss but fascinating nonetheless. – Rianne Peterson (Class of 2018) |
Tritonia festiva Tritonia festiva (also known as the Diamondback Tritonia), is a nudibranch of the family Tritoniidae. They are distributed all the way from North-Central Alaska to Baja California, and are 2-3cm in length. Tritonia festiva use their sensitive frontal veil to hunt their prey, carefully positioning their mouth over expanded polyps of octocorals before swiftly attacking. If you ever get the chance to look at an octocoral colony after a Tritonia attack, you will see holes where the missing polyps have been torn out by the nudibranch. I would say Tritonia festiva is definitely one of the prettier sea slugs, though there are over 3,000 sea slug species. Like other sea slugs, they are hermaphrodites, and so can mate with any individual passing by them. – Ashley Pierson (Class of 2018)
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