Friday Harbor Lab Tide Bites

A Sunflower Star is Born

By Jason Hodin, senior research sci­en­tist, Fri­day Har­bor Labs. 

Among the world’s hun­dreds of types of known starfish (or seast­ars as I’ll call them), our Pacif­ic coast sun­flower stars are true record breakers.

They are the largest seast­ar in the world, with an arm-tip-to-arm-tip “wingspan” of more than two feet when ful­ly grown. Using their thou­sands of tube feet, sun­flower stars can glide a hun­dred-yard dash in under an hour; cer­tain­ly bronze medal speed at least!

Contributed Photo/J. Hodin. Sunflower stars found by Richard Emlet in the intertidal on San Juan Island, July 2019.

They’re well known to ocean lovers for their bril­liant col­ors, and to marine biol­o­gists for the fear they invoke in their many types of prey. Con­tact with a sun­flower star will cause seafloor species – such as scal­lops and sea cucum­bers – to defy their rep­u­ta­tion as seden­tary crea­tures and swim, in a des­per­ate attempt to escape the clutch­es of the star’s 21+ arms.

Recent­ly, sun­flower stars broke anoth­er record, but one less wor­thy of cel­e­bra­tion: of the dozens of west coast seast­ar species impact­ed by a mys­te­ri­ous syn­drome known as seast­ar wast­ing dis­ease, sun­flower stars were hit the hardest.

Start­ing about eight years ago, sun­flower star pop­u­la­tions up and down the coast start­ed to plum­met, with the syn­drome turn­ing these majes­tic beasts into piles of goo.

They have now all but dis­ap­peared from the south­ern part of their for­mer range, and their num­bers in our area and fur­ther north are dras­ti­cal­ly reduced.

This calami­ty led the Inter­na­tion­al Union for the Con­ser­va­tion of Nature to include the species in its lat­est “red list” of endan­gered species, the first such list­ing for any seastar.

Read more at fhl.uw.edu.

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