In this post I present the remaining species of sea stars I found at Vancouver Island. The more 'common' forms with five arms (with one exception). Left: giant pink star. Right: rainbow star.
The blood star, Henricia leviuscula leviuscula. Henricia's are very difficult to identify. There are also a few subspecies, hence the double leviuscula leviuscula.
Philip Lambert notified me about the species in this post: 'You have homed in on three of the most difficult genera to distinguish from a photograph. I am far from certain for the Henricia without having them in front of me under a microscope. Even then, this genus is being studied by some others using DNA analysis, and they are finding more species. So it is an evolving study!' Just as Christopher Mah wrote (see bottom).
As I have written in an older post: in the future we just pick up our DNA-tricorder that tells us which species we have found. But then - after years - we long for yesterday when we had to study it ourselves. Then things were still a bit of a mystery. Those were the days!
Henricia leviuscula leviuscula (possibly). The blood star is not a very active hunter: it feeds on plankton, small organic matter, bryozoans and a few sponges. Species up to 32 cm across.
Again Henricia leviuscula anectens. The arm tips of blood stars are often slightly tilted upwards.
Evasterias troschelii, the mottled star embracing its prey. A typical posture for a lot of sea stars. Lambert (2000): 'To eat a bivalve, E. troschelii everts its stomach and inserts it between the shells while the tube feet pull from the outside. A specimen with an arm length of 22.5 cm can exert an average force of 4500 grams for six hours and a maximum force of 5500 grams.'
Up to 60 cm across.
Up to 10 cm this is - at last - a smaller species. It is remarkable how many species of sea stars are to be found in these waters - Lambert (2000) describes at least 43 (sub)species - and how big they can get.
Another six-rayed species: Leptasterias aequalis. Philip Lambert: 'it has more slender arms than the one above, and even rows of plates.'
A typical intertidal species: they are very sturdy and well adapted to heavy surf. For more information on the species, look here.
Many thanks to Christopher Mah (see echinoblog) and Philip Lambert (author of Sea Stars of British Columbia, Southeast Alaska and Puget Sound; see Literature) for helping me with the identification of quite a few sea stars and other information.