mollusk with two asymmetric shells attached at hinge. Shell
weight and shape vary greatly depending on age, location
and growing conditions. Shell color usually gray-brown.
Left shell, attached to substrate, is usually more deeply
cupped. Muscle scar purple in color and found inside the
shells where adductor muscle attaches.
are filter feeders and capture phytoplankton, dissolved
organic material and other appropriately sized particles
from the water column as food. Adults accumulate glycogen
reserves (fatten) during the winter months and develop ripe
gonads during early-late spring. Rising coastal water temperatures
stimulate external spawning of eggs and sperm by adults
generally in the late spring/early summer. Planktonic, swimming
life stages include trochophore larvae, which develop within
the first 24 hrs after fertilization, then into shelled,
veliger stages (D-hinge, umbo, late umbo and pediveligers).
Tides and currents carry the larvae throughout the estuary
for 12-21 days until pediveligers settle and crawl to find
suitable hard substrate to attach and undergo metamorphosis
into sedentary stage (spatfall). Spat (<1 inch) grow
to seed (>1) and adult sizes (>2) with increasing
shell size. Adults form vast reef communities providing
critical estuarine habitat.
are euryhaline and can survive in nearly freshwater, but
salinities <10ppt inhibit gonadal development. Spatfall
increases with increasing salinity, but predation and disease
stymie recruitment to seed and adult sizes above 15ppt,
depending on location within the estuary.