The Daily Bucket is a regular feature of the Backyard Science group. It is a place to note any observations you have made of the world around you. Snails, fish, insects, weather, meteorites, climate, birds and/or flowers. All are worthy additions to the bucket. Please let us know what is going on around you in a comment. Include, as close as is comfortable for you, where you are located.
As a followup on our low tide stroll yesterday, are you ready for some titillation? We're talking orgy here. Found this going on while walking down the beach that afternoon, at the rocky end.
mass coupling among hundreds of Frilled Dogwinkles
The Frilled Dogwinkle (
Nucella lamellosa) is a type of whelk, a ruthless predatory carnivore of the sea. These ones are not very frilly, but there's tremendous variation in frilliness, and color, in this species. They feed by drilling a small hole in a prey's shell, injecting digestive fluids to turn flesh into soup, and then sucking that out. At this moment, these whelks have put hunting on hold, so thousands of barnacles and mussels nearby can relax. Spring (loosely speaking) is mating season, and these have congregated to copulate and lay egg cases.
These ones are pretty big for the Salish Sea. The books say they can be up to 10 cm, but around here they don't get that big.
While land snails are famously hermaphroditic, marine snails are gender specific, and fertilization is internal. No telling which is which here, but obviously they are having no trouble.
The yellow, vase-shaped egg capsules, which are attached via short stalks to rocks well up in the intertidal and called "sea oats", are about 6-8 mm high with a suture line along one side. Each capsule holds about 550 eggs, each of which is 180 to 220 microns in diameter. Most of the eggs are infertile "nurse eggs" which the other embryos devour as they develop. Development within the capsule takes about 2.5-4 months. Ten to 20 juvenile snails hatch from each capsule (there is no free planktonic stage). A single female may produce a cluster of up to 300 capsules.
Note that even the embryos are carnivorous.
Snails do everything slowly, and judging by how closed up they are, right now they are resting up for the next round, when the tide comes back in. Several were lying on their backs (I did NOT tip them over).
brown operculum (lid) closing off shell-opening, conserves moisture, deters predators
N. lapillus egg capsules
Factoid: A close relative of our Frilled Dogwinkle,
N. lapillus in the Atlantic, produces the same purple bromine-based dye the Romans extracted from Murex snails to make their extremely valuable royal purple. The snails use the substance in a secretion for defense, and as an antimicrobial lining in their egg capsules.
Tyrian purple dyed wool
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BONUS gastropod intertidal spring sex: These are eggs cases of a nudibranch. Nudis ARE hermaphroditic, exchanging sperm, both laying eggs
I imagine many of you folks are covered in snow right now - take care of you and yours and your companion creatures! Any more spring observations, fellow nature-lovers?