Dive Dry with Dr. Bill

#561: Eight Arms to Hold (And Eat) You

I'm not a big fan of Halloween... I saw enough "ghosts" when I lived down at Toyon to last me a lifetime. Just check Rob Wlodarski's book Haunted Catalina for a few examples. Of course as a scientist, I really don't have a clue what those "spirits" were... but I know some of the incidents were rather unnerving! So instead of staying up at the house to get frightened to death by the little goblins and ghouls this year, I chose to submerge into King Neptune's domain once it got dark. It seems too many of our kids lack the energy to climb up my hill and then all the flights of stairs, so I end up eating the candy myself. Burp!

Before I suited up, I started to think about what I might encounter down there. I just hoped the black ghost fish (Apteronotus albifrons), ghost pipefishes (Solenostomus spp), goblin sharks (Mitsukurina owstoni), witch flounders (Glyptocephalus cynoglossus), vampire fish (Vandellia cirrhosa) and their kind didn't get me! And I wasn't willing to even consider the possibility of a great white on my dive... fortunately I still haven't acquired enough "bioprene" to be considered a tasty alternative to seal or sea lion for them.

I can tell my seven month long string of night dives (which I refer to as "vampire dives..." you understand if you've seen my fangs!) is coming to an end soon. The water is slowly chilling a bit (although still quite comfortable) and the cursed exotic Asian Sargassum is starting to choke out native species and prevent me from finding subjects to film. However, the real stopper is the "long" drive home in a wet wetsuit in my golf cart! Once I get back, drag all my gear up the four flights of stairs and wiggle out of my wetsuit; I'm ready for a hot shower, my bathrobe and hours in front of the computer editing the video footage I shoot.

Okay, Dr. Bill, get to the point... what did you shoot? Well, diving on Dia De Los Muertos (the day of the dead), I expected to find a lot of munching... but didn't. I did get to play with one green abalone. I gently lifted it off a bed of algae and placed it upside down to film it turning over. After doing this trick several times, I rewarded it by feeding it a nice big juicy blade of giant kelp. When I got home, I treated myself to a nice big bowl of kelp... in the form of ice cream! Yes, alginates from kelp are used in the making of ice cream so I ate my "vegetables."

This week's column is actually about something I filmed the night before. Finally I get to the point! A few weeks ago I filmed an octopus attempting to grab a kelp crab for dinner. It got pinched and retreated still hungry. On this dive I located another fair sized two spotted octopus ((either Octopus bimaculoides or Octopus bimaculatus) and filmed it as it roamed the reef, shot up into the kelp and then returned to the rocks. It didn't seem very concerned by my presence and stayed out in the open. Then, all of a sudden, a blacksmith (Chromis punctipinnis, the garibaldi's blue damsel relative) darted out from a crevice... and one of the octopus' arms shot out and grabbed it by the tail! The blacksmith wriggled free, but within a few seconds the octopus had captured another blacksmith using all eight of its arms and enveloped it with its mantle.

I knew octopus could capture fish to eat. I've even seen video of a GPO (giant Pacific octopus) capturing a small shark in an aquarium. However, I had never seen or filmed this in our waters. The blacksmith struggled several times to free itself without success as the octopus dragged it along and sought shelter. After a minute or so, the octopus found the hole it was seeking and started to enter it... spooking another blacksmith out of its hiding place. I watched (and filmed) as the octo pulled the blacksmith into its lair. The damsel made one last valiant attempt to escape, and nearly succeeded, but finally disappeared down the hole. I've never tasted blacksmith and would have probably preferred crab, but this octo must have known what it was doing.

As a kelp forest ecologist, I've often said that one needs MANY hours of observation to better understand the relationships involved in an ecosystem. Over many decades I have spent thousands of hours underwater observing and later filming the interactions between critters, yet this is the first time I have actually witnessed an octopus capture and munch on a fish. It may happen many times a day around the island, but not when I'm in the vicinity. Each new observation like this adds a new piece to the jigsaw puzzle of the ecology of the kelp forest. I just feel a bit sorry for the poor blacksmith since they seem to be on almost every carnivore's menu... kelp bass, morays, etc.

© 2013 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 29, 10:00 AM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. You can also watch these episodes in iPod format on YouTube through my channel there (drbillbushing). Please help me climb out of self-imposed poverty... buy my DVD's (see this link). Yes, take Dr. Bill home with you... we'll both be glad you did!

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Octopus high in the kelp, then (arrow) encountering blacksmith in the open and
capturing one hiding in a crevice then dragging it (arrow) off for dinner.

This document maintained by Dr. Bill Bushing.
Material and images © 2013 Star Thrower Educational Multimedia