Thursday, October 8, 2009

Sea Urchin Video FRIDAY!

Here's some sea urchin videos to tide everyone over for the three day weekend! Happy Columbus Day!

Red Sea (Strongylocentrotus franciscanus) Urchin Barren-Cal Fish & Game ROV video

Fire Urchins from the Indo-Pacific!

Purple Sea Urchins (Strongylocentrotus purpuratus) from Santa Cruz with some Pisaster giganteus action going on at the end...

Echinus acutus
from the Aquarium de l'institut Océanographique de Paris


tshilson said...

Some of the videos show a LOT of sea urchins. Is that a normal/healthy number or are there too many, such as when a predator population is reduced?


(I am a volunteer at the North Carolina Aquarium and sometimes explain/show sea urchins to our visitors.)

ChrisM said...

Well..yes and no. A healthy sea urchin population can naturally include quite an abundant number of individuals. But these are often kept in balance by various predators or other variable environmental factors.

But the classic example is the effect of otter removal from a kelp ecosystem resulting in runway sea urchin growth and consequent "urchin barrens" resulting from the onslaught of continuous grazing and so on...