crabs and lobsters

The VLM has many species of invertebrates and almost every common crab species found in VA and a few that aren't. Of course we display the iconic blue crab Callinectes sapidus, but also several hermit crab species, mud crabs, ghost crabs, two spider crab species, and the ancient horseshoe crab Limulus polyphemus who are more closely related to scorpions and spiders than true crabs. In addition to these relatively common species we have some more unusual species - the beautiful calico box crab, stone crab, portunid crab, and the giant red hermit crab - that are more common further south than Virginia. We also display the Atlantic lobster and the miniature freshwater counterpart the crayfish (in an unusual blue phase and red phase, pictured below)

We collect these animals (sometimes on accident) most often as juveniles and have them for several years. As they grow, they must shed their shells or exoskeleton and form a new shell; these discarded shells are called molts. Molting can be a very dangerous time for these animals. Their shells are ordinarily a hard protective armor against predators, but immediately after molting their shells are soft, leaving them vulnerable to predation even by humans; soft shell (blue) crabs are considered a delicacy by many people. The process may take many hours and they may not harden up for days. Female blue crabs mate at this stage and are "covered" by the males. A previous blog shows the entire process of a calico box crab molting. Not only are the animals vulnerable, but many things can go wrong during the process and result in deformities, loss of limbs, even death. 

In captivity, proper nutrition and excellent water quality are critical for the proper shell development; pH, ammonia levels, and trace elements in sea water (mg, Ca, P) seem to all factor in to molting success. Poor nutrition or water quality may result in malformed shells, shell necrosis (pitting) or death. We vary their diets as much as possible to ensure complete nutrition. Diets include: live clams, shrimp, squid, herring, mackerel, capelin, Mazuri gel diet and Ulva (a green algae). Species such as the blue crab will molt many times in their lives, growing up to 30% each time! Eventually they reach a terminal molt, a size at which they will grow no larger.

The aquarium staff keeps and carefully dries out the fragile molts for educational use, or even as decoration. Below is a picture of our latest lobster molt ( the yellow ruler is 6 inches) and various molts that adorn my office:



Collecting season

As the water warms this spring, our collecting opportunities expand. I generally have a mental list of species we would like to have here, but there are always fishes we need each year as they outgrow their exhibits and are transitioned to larger ones (e.g. striped bass, flounder). Some species are popular not only among guests and staff, but other facilities often inquire about for trade, such as lookdowns and spadefish. Fortunately, I have many locations that I have catalogued over my many years in VA through personal experience, research/professional (VIMS) or through the museum. 

Juvenile Spadefish, a popular catch each summer

Collecting (with requisite permits of course) is one of the more pleasurable parts of this type of work. Although I never truly enjoy taking an animal out of its element, I use that sentiment to ensure a personal and professional quality of care for the animals we do keep. I DO NOT keep animals I feel are unsuitable for captivity, doubt we can handle, or care for adequately. And there are many species I would like to have, even have had, but do not fit that requirement (octopus). Back to the pleasurable part; it is hard to beat late spring through fall in VA. July and August can be brutal at times, but then again we are in the water when collecting. 

Moonfish

Most commonly we use a 100 x 6 foot beach seine that I acquired from my old bosses at VIMS originally used for the Juvenile Bluefish Survey. It needs repair after just about every trip anymore but it is very effective. Not only is the weather and scenery a huge highlight of collecting trips but it is also the thought of getting interesting fishes that we rarely see or do not currently display. Every now and then there are a few surprises - bluntnose ray pups (13 total), banded drum, leatherjack, moonfish - and large scale changes in species by year (2010 was an excellent spotted sea trout/bluefish year, 2009 was a striped bass/flounder year).

Bluntnose Ray pup caught at Cape Charles

So this year we can look forward to the unexpected and we certainly expect to enjoy it.

Skate Exhibit up and running

A few months ago on a recreational trip to Oregon Inlet, North Carolina I noticed an unusually large amount of flotsam around the southern jetty. Always on the lookout for interesting exhibit props, I discovered wooden poles, formally from a pound net, that would make excellent pilings in the skate exhibit. Treated wood is toxic for fishes so wood pilings could not be purchased, and our budget would not allow for fabrication of pilings from textured cement.

So...two aquarium staff members went down ASAP and discovered the wooden poles still washed up and left on the beach. They then sawed the pole down to five, 5- foot sections and brought them back to the VLM. The new "pilings" were then drilled through the bottom to hold bolts and lightly scrubbed and set aside for the project of remodeling the Skate/Ray Exhibit. The stingray that was then on exhibit was removed to a holding system, and the renovation began!

The next step was to drain the exhibit. Then the substrate was removed. Outside of the tank, the five pilings were attached to a large piece of high-strength resin that served as a base to keep the pilings stationary and stable. After the piling structure was installed inside the exhibit, sand that had also been previously collected and washed was then added to cover the base, and the tank was filled. We let the tank run for a few days and plumbed in a chiller before placing the animals in the new habitat. Once the chiller was installed, the exhibit was ready and now home to three Little Skates (Raja erinacea) and five spotted hake (Urophycis regia)!

                       Notice the diamond - shaped outline of the skate in the center of the sand!

To the left, a hake is poking out of the sand. On the right, notice the skate's outline in the sand.

RAW 2011 - by Patrycja Lawryniuk

On Tuesday and Thursday of this week, my colleague Jessi Shupe and I attended the Regional Aquatics Workshop (RAW), hosted by the Virginia Aquarium in Virginia Beach, VA. At the workshop, we attended lecture sessions with different speakers from all over the world!

On Tuesday, the sessions focused on water quality and life support systems, fee-based and animal interactive programs, and fish propogation. It was really neat to see what other facilities do with their animals. I even learned how to get started on any potential animal-interaction programs. I was especially interested in all Jeff Marliave from Vancouver Aquarium had to say on catching and raising wolf eels.

Thursday's sessions focused on husbandry, animal enrichment, and exhibit design. These three sessions were particularly useful to me as an aquarist, and the animal enrichment/behavioral conditioning was especially interesting. I really enjoyed learning how to train eagle-spotted rays and white sea bass to feed by hand. I also walked away with multiple new ideas for changing and maintaining our exhibits.

Overall I had a very pleasant experience at RAW 2011, and I really appreciate the museum allowing us to experience the workshop; we had a great time and learned a lot.