Weed of the Week: Killer Costumes

I love seaweed. Maybe it’s because I am from California and we are all plant loving hippies or maybe it’s because they’re the underappreciated overlords of the sea and I respect that. Seriously though, without these photosynthesizing wizards, life in the ocean would cease to exist. Thus, in an attempt to bring appreciation to the lower bits of the food chain, I give you Weed of the Week. For the next month, I will focus on different species and highlight the various reasons that these weeds represent a force to be reckoned with. 

HT to Dr. Martini for our slightly inebriated stroke of semi-genius. I hope this helps you realize that not all squishy things in the ocean are gross. Some are indeed, epically badass.


With Halloween right around the corner, tis the season to break out those costumes and spend a night being the one thing you have always wished you could be. For some, it’s sexy Dinos, or sexy Big Birds, or sometimes we can even get to those special unmentionables (faith in humanity where art thou?).

Look at me! I'm so pretty! Source: Cornwall Community News

Look at me! I’m so pretty!
Source: Cornwall Community News

Regardless, for those of you looking for that one costume that really kills, might I suggest taking some fashion advice from the decorator crab Libinia. Just do what they do and go as the sexy seaweed, Dictyota menstrualis. Now I know what some of you are thinking, “If I were a decorator crab…wouldn’t I want to decorate my shell with something a bit more fabulous for Halloween? Not some janky brown seaweed?” Well if you were this guy, then maybe>>>>

But if you were a little crab out on the rocky reef all by yourself on a dark hallows night (or any night for that matter), trick-or-treating from cave to cave can be a pretty cut-throat business. This is the one  (and only) occasion where purple sparkles just won’t do.

Thus, in order to avoid becoming a treat themselves, Libinia got smart. You see, Dictyota menstrualis isn’t just any old sexy seaweed nonchalantly used for crabby camouflaging. No. Rather D. menstrualis is chalked full of nar nar chemicals like Dictyol E . Not only does the crab use this chemical to find and hone in on Dictyota, but he chooses this seaweed above even the most abundant ones to decorate his shiny carapace with.  Now logic would lead us to believe this is a pretty bad move on crabby’s part. If you want to blend in, why in the hell are you not picking the most abundant seaweed to decorate with?!?! Stupid Crab….

No. You can't see me.  Source: J. Stachowicz

No. You can’t see me.
Source: J. Stachowicz

But this is where we get to the seaweeds being the most badass organisms in the ocean part (i.e. my favorite part). Remember when I said that Dictyota is chemically nasty.  Well, most of the fish know this and so does our little crabby friend. So what does he do? He decorates his shell full of Dictyota and voilà!! becomes chemically defended himself. Fish avoid him. A survival win. Who does all the work and gets hardly any of the credit? The seaweed.

So tomorrow, when you went with the sexy dolphin and not the sexy chemically-defended seaweed and you start to get preyed on by all them crazy fish out there. Maybe next Halloween….You’ll think twice.



This Weed of the Week brought to you by: 

Stachowicz, JJ, ME Hay. 1999. Reducing predation through chemically mediated camouflage: Indirect effects of plant defenses on herbivores. Ecology. 80(2): 495-509.

Alex Warneke (112 Posts)

Alex is committed to a life of inspiring others to view science through a more dynamic and empowering lens. Alex obtained her M.Sc. in Chemical Ecology from San Diego State University and most recently resided as a Science Programs Manager and Marine Scientist for the National Park Service. As an ecologist, storyteller, and community engager, she has spanned critical boundaries between stakeholders in education, academia, non-profit, and government to translate the most current scientific bodies of work in ways that are accessible and inclusive. She is a strong proponent of unconventional science communication and extending the broader impacts of science to the public using the outlets of art, digital media, education, and citizen science. Currently, Alex works at the interface of climate resilience and community with the Climate Science Alliance. As Deputy Director for the Alliance, her hope is that through her work and experience she can get the world to think differently about how we connect and impact the thriving ecosystem around us and commit to fostering a more resilient future.

4 Replies to “Weed of the Week: Killer Costumes”

  1. This article reminds me of Dream Fish – sarpa salpa fish that eat caulerpa taxifolia which in turn makes their meat hallucinogenic. Yes, ichthyoallyeinotoxism is just too much fun to type.

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