Hood Canal, Washington – Of all of the fascinating creatures who inhabit our Salish Sea intertidal zones, few are as showy or delight people as much as the sea star. I took my 90 year old grandmother from Arizona to see the Oregon Coast for the first time. As she was leaving to return to Arizona, the airport security screener asked her about her visit. Her delightedly girlish response, “I got to hold a sea star!”
Around our Salish Sea, we are blessed to have a large variety of this popular echinoderm guaranteed to delight Wonder Trackers of any age. While the well-publicized wasting disease has impacted populations of our sea stars, in many areas, a sharp eye at a substantial low tide will still yield as many stars as you will find on the Hollywood Walk of Fame!
Sea stars (or starfish) are the echinoderm family members with arms (rays). If you took those arms and pinned it to the central disc, you would have its relative, the sea urchin. Were you to flatten that urchin, it would be another close relative, the sand dollar. Taking that a step further, if you pinned the sea star’s arms to its central disc and stretched it, you would have a third relative, the sea cucumber. All of these beautiful creatures share a common radial symmetry, with no head or brain, and a structure of separate plates which have external spines.
They also share an amazing water-vascular system which allows them to move and feed. In the case of the sea star, this system draws water into the body via an opening on the top of the star called the madreporite. The water then flows into a series of canals that branch off into thousands of tube feet on the underside of the sea star. These tube suckers are connected to bulbs called ampullae which operate like the turkey baster in your kitchen. When these ampullae are squeezed, the tube feet elongate, creating a suction-cup effect that anchors the sea star and allows it to grip its food. But, as they relax, the tube feet retract, allowing it to move.
So what is Sea Star Wasting Syndrome?
In recent years, sea stars populations have been decimated by a mysterious illness called “Sea Star Wasting Syndrome.” Researchers first noted the syndrome in 2013. While this condition has been seen before – in the 1970s, 1980s, and 1990s – those outbreaks were much more localized to the Southern California coast. In this recent epidemic, the wasting syndrome has reached an unprecedented scale and scope, ranging from Baja California, Mexico to the southern shores of Alaska.
The first signs of the syndrome are lesions on the rough, outer skin of the star. Within days, the lesions spread and arms fall off, leaving nothing but a ghostly blob of tissue. A star can go from one lesion to death in a matter of days.
Working to understand the SSWS is the Multi-Agency Intertidal Network (MARINe), a consortium of 18 research groups that report data from over 200 stations up and down the Pacific coast. A recent report analyzed data from over 90 intertidal sites along the North American Pacific coast. It compared data from 2000-2016 to study the impact of SSWS. The data revealed that once again, Southern California saw the greatest loss of sea stars, with over half of the sites reporting a 99 percent or greater loss of stars.
Ochre stars (Pisaster Ochraseus) were the hardest hit, although other species such as the spiny pink and mottled were also impacted. Interestingly, other echinoderms, such as sand dollars and sea cucumbers, seem unaffected.
Unfortunately, what remains unknown is the cause of the syndrome. Some scientists attribute it to a viral pathogen. Often times, this type of event is attributed to sea warming due to El Nino events in the Pacific. However, that does not seem to be the case with this outbreak. Others feel it is simply nature’s method of dealing with an overabundance of a particular species, no reason for great alarm, and that species will rebound to healthier levels.
So, what is the future of our beloved echinoderm? For now, the future is uncertain. Juvenile populations in the northern regions of the affected area seem to be sustaining. If that continues, perhaps by the end of 2018, we will be able to say that the crisis has passed. Hopefully, this means that other people’s grandmothers will be able to feel the same thrill at holding a sea star as mine did those many years ago.
Cultivate Wonder… Discover Design
Where and When – Sea stars are found throughout coastal areas of the Salish Sea in both mudflat and rocky intertidal areas. They can often be found clinging to the underside of rocks or pilings – pretty much any area where California muscles are to be found. The most commonly seen star is the Ochre star, which can range from brown to orange to purple in color, as these stars can survive the mid-intertidal zone and thus are easier to spot. However, spiny pink and mottled stars are also commonly seen in the region. At lower tides, leather stars are frequently seen.
Sea stars are also common on the outer coast of Washington, as well as up and down the Pacific coastline of western North America. Best times for viewing are during minus tides, which increase the chances of seeing several species of stars, as well as fellow echinoderms – sand dollars, sea cucumbers, and sea urchins. In the Salish Sea, the best daytime low tides are during the late spring and summer months, which makes for comfortable viewing temperatures, as well.
Wonder Triggers for Young Tackers
- Build a model of the sea stars tube feet (ampullae) by taking a household turkey baster filled with water. Securely attach a small balloon to the small opening of the baster. Squeezing the bulb of the baster, fill the balloon and then release to draw the water back into the baster.
- Multiple sea star varieties are often found near each other. What differences do you see between species? What things are similar?
- Try holding a sea star! Make sure your hands are washed with no sunscreen or soap on them. Do not pry sea stars from rocks. But, if it is lying in muddy or sandy areas, gently pick it up, keeping it under the water if possible. Let it rest it in the palm of your hand. What do you feel?
References and Resources
Images – SPegany, Copyright 2018