Native SpeciesKnotted wrack

Ascophyllum nodosum
FOUND by DoomsdayBunniesCM
ID Confirmed
Quality checked by Ms H
Peer reviewed by HS
Field Notes
On October 5th, 2015, our class went to Town Landing. The air was surprisingly warm for the beginning of October and the air was fairly mild. The wind was light with occasional gusts that chilled the air. The sky was bright blue but littered with altocumulus clouds. Closer to the docks the smell of fish was very ripe, almost to an eye-watering point; farther to the right, where we were positioned, the smell was not as strong, it just smelled like ocean: strong, salty, and almost rusty. Our quadrat was placed on the shore on a muddy, sandy piece of land. A few days before we had record amounts of rain from a hurricane from just off the coast. When standing from the shore and looking at the quadrat, there was a large mass or rocks to the left. Directly to the front and to the left there was a small rock covered in some Ascophyllum Nodosum, or knotted wrack, and some other seaweed. Our quadrat was placed with the top right corner on a rock with the knotted wrack directly in the middle. There were no other species, native or invasive, that interfered or even came close to the knotted wrack. The only thing noticeable about it was the knotted wrack was laying across a rock and the edges were on top of some bladder wrack. After speaking with some other groups they said they saw the green crab taking cover in the knotted wrack. Though I personally did not witness it, the fact is no surprise because the knotted wrack is a common home for up to one hundred animal species. The crab was buried deep within the alga, something our group saw from from the green crab but in different plants.
Supporting Evidence
Photo of my evidence.
The knotted wrack has an axial growth pattern. In other words the branches are grown randomly off of the single stem. Though less visible in this image, the cross section was flattened. Though easily confused with the bladder wrack you can tell it is not because there is no vein or midrib that runs down the middle.
Photo of my evidence.
From this image you can see the rubbery texture of the alga and the long branches. On this individual plant, the branches grew up to 50 cm long.
Photo of my evidence.
The knotted wrack is olive and green-brown-yellow in color. The air bladders are egg shaped found randomly on the branches.
Species Observation: Species Looked For
Did you find it?: 
I think I found it
Scientific name:
Ascophyllum nodosum
Common name:
Knotted wrack
Is it alive?: 
Some dead & some alive
Count of individuals: 
Between 1/4 and 1/2
How big is it?: 
Greater than 10 cm
Is it male or female?: 
Can't tell
Sampling method: 
Quadrat (user-placement)
Time search
Photo of our sampling method.
Place Studied
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Map this species
N 43.731620 °
W -70.205280 °
Observation Site Information
A photo of our study site.
Coastal - Rocky intertidal
Trip Information
Falmouth Town Landing 2015
Trip date: 
Mon, 2015-10-05 14:08
Town or city: 
Type of investigation: 
Species and Habitat Survey
Time of low tide: 
Mon, 2015-10-05 11:34
Habitat Observations
Species diversity: 
10 different species
Evidence of vectors: 
Recent disturbance
Water temperature: 
Dissolved oxygen: 


Hi DoomsdayBunnies (love the name),

Great observation! From the wonderful field notes to the great photos and descriptions your observation really has it all. I especially liked your field notes (altocumulus clouds - nice!) they really did a great job describing your site conditions and what your peers were finding versus what you found.

Great written evidence too - you did a great job ruling out alternative species and describing different aspects of your specimen. Your photos are clear and really beautiful to look at. You did a nice job capturing how this algae looks on the shoreline with its crazy olive color.

I've nominated your data for the "Best of Vital Signs" page.

Thanks for posting and happy observing!

Hi Moss Boss,

Thank you so much for the kind words. I am so glad that you liked the pictures and your nomination means a lot to me!

Thank you again for putting the time into reading my report and for leaving me a comment.