Related Resources
Hatching a Plan for Blue Crabs
Farmers, Warriors, Builders: The Hidden Life of Antsat the Smithsonian's National Museum of Natural History
The Inverteberate Exhibit's Blue Crab and the Bay exhibit highlights the biology
and ecology of the blue crab, Callinectes sapidus, focusing on
its life cycles and its environment in the Chesapeake Bay.
There are 3,600 plants and animals that call the Chesapeake Bay home. The bay itself constitutes a watershed about 64,000 square miles in size, ranging from New York state to Virginia. We all benefit from the health of this expansive and valuable ecosystem.
This exhibit introduces visitors to the unique nature of our local neighbor, the blue crab, and aims to inspire them to take action with the exhibit's cooperative environmental partners. Conservation issues associated with the Chesapeake Bay watershed, the largest estuary in North America, are highlighted. Stop by the National Zoo’s Invertebrate Exhibit and find out what you can do to help conserve our local environment.
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| The Chesapeake: one
big watershed The Zoo’s storm drains are just a tiny piece of the enormous puzzle that makes up the Chesapeake Bay watershed. Over 16 million people live near the more than 100,000 streams, rivers, springs, and wetlands that empty into the Chesapeake. |
Blue Crab Range
Roughly translated, the blue crab’s scientific name,
Callinectes sapidus, means “beautiful swimmer
that tastes good.” This unique crustacean (related to
other crabs, shrimps, and lobsters) ranges along
the Atlantic coast from Maine to Florida, along the coast
of the Gulf of Mexico, and into the Caribbean Sea. These crabs
are truly a colorful species, with shades of red and opal
blue shell coloring developing as they grow.
Blue Crab Lifecycle
As they age, crabs undergo a process known as molting—they shed their old shell in order to make room for the growth
of a new shell forming underneath. After a crab has molted
and shed its shell, or exoskeleton, it is termed a “soft-shelled”
crab, and is vulnerable to everything from larger marine predators ,
including fishes and other crabs, to humans.
These crabs, which live up to about three years, undergo numerous molts throughout their lives, after starting out in seven different larval, or floating planktonic body forms, until they progress into miniature versions of their adult form.
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| Mason Neck National Wildlife Refuge on the Chesapeake Bay. |
The Crab's Interdependence with the
Chesapeake
Right around the period of achieving this first true crab
stage, the juvenile crabs seek out the shelter of sea grass
and plant beds throughout the Chesapeake Bay or other estuary
grounds where they are found. These beds of vegetation are
referred to as SAV, or submerged aquatic vegetation, another
source of conservation measure in the bay’s ecosystem.
Reproduction
Upon maturing, which occurs at roughly 12 to 18 months of
age, males and females mate, where upon completion, males
will typically head for the lower salinity waters of the northern
Chesapeake Bay, and females will head for the more salty waters
in the south where the bay flows into the Atlantic Ocean.
Once the females are in these higher salinity waters, they
lay an egg mass otherwise known as an “egg sponge”,
which harbors up to about eight million eggs. As these eggs
hatch out, the process begins again.
Protecting the Population
Blue crabs are being fished to their capacity in the
Chesapeake Bay ecosystem. In some years, too many females
were caught in the harvesting of crab pots, and over the long
period of time, the population was unable to replenish itself
to its previous numbers. There have been numerous crabbing
regulations organized by local state governments and advisory
committees that aim to curtail these population declines
so this amazing animal will be around for years to come.
Regulations do not just apply to the crab itself, however. There are several major areas in need of further conservation efforts with regards to the entire Chesapeake Bay watershed. As mentioned above, the submerged aquatic vegetation that provides shelter for juvenile crabs has been under great decline this past century as a result of lower water quality and murkier waters as a result of soil and agricultural runoff, which spur the growth of unwanted algal blooms, and thus do not allow enough sunlight to be available to the growing aquatic plants. As the SAV declines, so does the capacity for the Chesapeake Bay to deal with nutrient input from these sources, but this also leads to dramatic declines in the amount of dissolved oxygen supporting other life in the bay waters.
Riparian buffer zones are under increasing threat as urban development continues. As more trees are removed from areas around the bay watershed, the prevailing soil becomes looser and less stabilized, thus causing greater runoff into streams and ultimately into the bay.
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| Where our water goes...
Water runs from our storm drains into Rock Creek, which runs into the Potomac River, which in turn, empties into the Chesapeake Bay—home of the blue crab. |
While you won’t find blue crabs living in the Zoo’s storm drains, they are affected by what goes into them.
Make the connection:
- Be careful with what you put down the drain, or flush—wastewater
that
leaves your home, yard, or business ultimately ends up in the bay. - Learn how to make your lawn and garden “bay friendly.”
- Get your neighbors involved by organizing a project to
mark your
local storm drains: “Drains to the Chesapeake.”
For additional information, visit the following websites:
