Several years ago I headed out to one of my absolutely favorite isolated dive sites in north Puget Sound to do one of my absolutely favorite things – feed a Giant Pacific Octopus. I knew exactly where to look because I had found his den about a month prior and had been feeding him ever since. Usually I simply grabbed a crab on my way down to the den, a large cave in the sand hollowed out under a colossal boulder, and dangled it in front of the opening. Soon, my huge friend would snake out a long twitching arm or two and take the tidbit out of my outstretched hand. This had been going on for weeks and he almost seemed to recognize me when I arrived.
Today I was trying something new, however, since the octopus had been doing a rather fine job of clearing out the local crab population. I had stopped on my way to the dive site and had bought some chunk chicken meat. I had plopped the chicken into my mesh "goodie-bag" and dropped down into the deep green waters of the Sound to see how my newfound friend liked KFC underwater style. At first he seemed reluctant, but eventually a single arm worked its way out of the den and explored the chunk of chicken I held in my hand. Suddenly interest increased, another arm lancing outward and the colors of the big octopus slightly changing as he dragged the chunk of chicken down into the den. This continued for quite a while, each time one piece of chicken disappeared I would reach back to my bag for another.
Until I reached back and the bag was no longer there…..
Turning to see what had become of it I was surprised to see two massive Sunflower Stars engulfing my mesh bag and dragging it away from me down the sandy slope. Out of the corner of my eye I caught some movement and, turning, I saw 4 or 5 more of the huge Sea Stars gliding down the slop toward the bag, obviously having picked up the "scent" of the chicken in the water column. Intrigued, all thoughts of the octopus forgotten, I watched as the newcomers reached the bag and a struggle ensued with the first two. Still more Sunflower Stars now came into view from multiple directions, all heading straight for the bag. Mesmerized, I realized that I was observing a feeding frenzy, albeit in slow motion. The struggle of the sea stars to get at the raw chicken can only be described as violent – slow, deliberate, but violent nonetheless.
Eventually, my bottom-timer told me that I was approaching the end of my planned bottom time and I reached out to stop the downward movement of my bag and reclaim it. This proved to be a task that was FAR easier said than done – each Sunflower Star gripping the mesh with hundreds of tiny tube-feet and some of them having everted their stomachs onto and through parts of the mesh in an effort to get at and devour the chicken. Lifting the bag up from the bottom, I suddenly realized how heavy several of these massive sea stars are, as well as how determined they can be when feeding. As I pulled each long arm from the bag they would attempt to latch back on and would often come in contact with my arms or gloves, each time leaving bits and pieces of their tube-feet clinging to my suit. Finally shaking the last of them off was like suddenly dropping a sack of potatoes and I briefly had to regain control of my buoyancy as I watched the last of the giant sea stars drift back down to the bottom, each of the others now heading off again on the hunt.
This was a side of these animals that I had previously not imagined. While hanging at my deco stops I pondered what I had seen that morning and decided then and there that I needed to find out more about these voracious and fascinating creatures. I also considered the fact that I never want to be lying dead on the bottom of Puget Sound, because these critters would be amongst the first to arrive!
The Sunflower Star, Pycnopodia helianthoides, is the largest sea star in the world, capable of reaching nearly 39 inches across (1 meter), tip to tip, with arms reaching up to 15 inches (40 cm) in length. In addition to being the largest, this species is also the heaviest of all sea stars, often reaching 11 pounds (5 kg) or more, especially when there is an abundance of food readily available. Having more arms than any other sea star species in the world, it comes by its common name, Sunflower Star, because of the large number of arms that it sports. Its scientific name reflects this, Pycnopodia meaning "many-legged" while helianthoides means "sunflower". The number of arms on adult specimens ranges from a minimum of 15 to a maximum of 24, making this sea star resemble a huge sunflower when viewed from above. Seemingly able to sport every color of the rainbow, these giant sea stars can be almost any shade - from bright yellow or orange to a shiny blue or purple and almost anything in between. The color of the animal is dependent on how much of the skin is exposed when the gills extend beyond the calcareous outer plates. The texture of it skin feels almost "flabby", although spines protrude all over its upper body and down the arms.
Like all sea stars, on their underside these animals have open "furrows" radiating down each arm that contain huge numbers of tiny tube-feet as well as both gonads and digestive glands. The massive number of arms thus gives P. helianthoides a huge advantage when hunting, giving it enormous predatory capabilities in terms of both speed and dexterity when compared with other sea stars. When actively searching for prey sunflower stars almost appear to glide over the bottom, every animal that can do so fleeing in all directions. Sights such as this astonish divers that would never have imagined a "lowly starfish" could move that fast without benefit of time-lapse photography. This species has been recorded as reaching 360 feet per hour (110 meters) when hunting, and can reach this speed on either sand or rock. These voracious animals can be found in the sub-tidal zone down to extraordinary depths – one specimen has been found as deep as 1,427 FSW (435 meters). Sunflower Stars can be found throughout the coastal areas of western North America, from the Aleutian Islands in the north to southern California, with one source that I consulted stating that they can be found as far south as Isla Todos Santos, off Baja California in Mexico.
While most divers probably consider them carrion eaters since they are often seen feeding on and covering dead fish and animals lying on the bottom, the sunflower star is in fact an extremely active predator. Throughout its massive range their prey-items are many and varied – sea urchins, abalone, sea cucumbers, and all manner of clams, shrimps and crabs making the menu list. I have personally seen a sunflower star overpower and envelope a Dungeness crab that was buried in the sand and had timed its escape a moment too late. A common hunting tactic of the sunflower star is to locate a clam under a sand or rocky bottom and then excavate the area around it faster than the clam can tunnel away. Divers finding large "pits" in the bottom of their favorite dive site will usually discover that these were in fact created by sunflower stars in search of a clam dinner. Definitely feared by other invertebrates, some prey species have developed escape responses necessary to survive when sharing an environment with P. helianthoides. Many ordinarily lethargic species will go to great efforts to escape the clutch of the voracious sunflower star. Abalone, for example, will whip their shells back-and-forth to break the grip when they sense a sunflower star has touched them. Urchins will direct their spines in the direction of the predator in an effort to fend it off and prevent it from getting a grip on their shell. Many species of clam will extend their foot and use it to "run" away by launching themselves off the bottom and rolling down slope, while some sea cucumbers, nudibranches and sea anemones will swim away in panic when they feel the slightest touch of P. helianthoides. Literally, when a large sunflower star sweeps through an area looking for food everything reacts – hiding, fleeing, or preparing to fight. Like most predatory sea stars, the sunflower star feeds by securing its prey with its arms and thousands of tube-feet, and engulfing its victim with its everted stomach, whether struggling and alive or rotting carrion.
The comparison to the toothy critter that fits the same type of role on the African savannah would seem to be appropriate - Pycnopodia helianthoides, the sunflower star of North America's west coast, is truly the "Hyena of the Sea".