Wednesday, August 27, 2014

August 11th - August 17th, 2014

Daily Low Tides

Monday, August 11th
Low tide: -1.4' @ 7:44 AM
Low tide: 0.7' @ 7:56 PM

Tuesday, August 12th
Low tide: -1.2' @ 8:27 AM

Wednesday, August 13th
Low tide: -0.8' @ 9:09 AM

Thursday, August 14th
Low tide: -0.2' @ 9:52 AM

Friday, August 15th
Low tide: 0.5' @ 10:35 AM

Saturday, August 16th
Low tide: 1.2' @ 11:22 AM

Sunday, August 17th
Low tide: 1.9' @ 12:16 PM

Notes from the week

The HRAP team spotted lots of nudibranchs, or sea slugs, this week, including the leopard, shaggy mouse, red (or Rostanga) and opalescent. These animals are molluscs-- as are snails, chitons, limpets, clams, squid, and octopus! Most molluscs have at least a bit of shell-- one notable exception being the octopus-- and even most sea slugs have a shell in their larval stage. Sea slugs often specialize on a cnidarian (animals with stinging cells, like jellyfish and anemones). Not only are they undeterred by these animals' stinging cells (or cnidocytes) but they actually store them in their bodies and use them as their own defense! They pack these cnidocytes into their cerata, the fleshy tubes projecting from the backs of many nudibranchs, including the shaggy mouse and the opalescent.

In bird news, the oystercatchers valiantly defended their nest this week against seagull intruders. Also, the gull chicks are officially fledging! HRAP staff observed the chicks testing out their wings on Monday.

Yet more Velella velella are washing up on Cannon Beach. Jellywatch.org, a site maintained by folks at the Monterey Bay Aquarium Research Institute, have come up with a fun and easy Velella citizen science experiment. Velella's characteristic sail is twisted to the left or to the right (an anatomical quirk that can have big consequences for the jelly)-- to participate in this "experiment," note the twists of 10 Velella. If all ten twist the same way, note how many more you have to count before you find an individual that twists the other direction. Check out the jellywatch page about Velella for more information.

Creature Highlights

HRAP staff spotted a cabezon in the tidepools this week.

If you're having trouble spotting this fish, then its camouflage is working!

Cabezon, named for their big heads, are a predator of the nearshore and intertidal. And humans, in turn, are predators on them! These are considered a game species-- which makes more sense when you realize they can grow a lot bigger than the individual photographed, up to 23 pounds.


Birds
  • Black Oystercatcher (Haematopus bachmani)
  • Western Gull (Larus occidentalis)
  • Tufted Puffin (Fratercula cirrhata)
Intertidal
  • Purple sails (Velella velella)
  • Red rock crab (Cancer productus)
  • Ochre star (Pisaster ochraceus)
  • Leopard nudibranchs (Diaulula sandiegensis)
  • Shaggy mouse nudibranch (Aeolidia papillosa)
  • Red nudibranch (Rostanga pulchra)
  • Leopard nudibranch (Diaulula sandiegensis)
  • Opalescent nudibranch (Hermissenda crassicornis)
References

Ruppert, E. and Barnes, R. Invertebrate Zoology. 6th ed. Thomson Learning. 1994. 

Kozloff, E. Seashore Life of the Northern Pacific Coast: An Illustrated Guide to Northern California, Oregon, Washington, and British Columbia. Seattle and London: University of Washington Press. 1993.

Sept, J. D. The Beachcomber's Guide to Seashore Life of California. Revised edition. Madeira Park, B.C.: Harbor Publishing. 2002. 
http://aquarium.org/exhibits/passages-of-the-deep/animals/cabezon Accessed 8/26/2014



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