Saturday, July 27, 2013

Juvenile sandbar sharks - video!

We recently acquired two sandbar sharks (Carcharhinus plumbeus);one male and one female. They are in quarantine at the moment and may not be on display for a while, but this video provides a sneak peak. The smaller of the two is a female and likely only a couple of months old. More about where/how we got them, details about their care, and what we have planned for them very soon...

Saturday, July 13, 2013

Blenny fight! A dominant male protects his food (little neck clam)

A dominant male (blue spot on the dorsal) fights others away from the freshly shucked clam in our piling exhibit

Feather blennies are named for the two cirri or "feathers" over their eyes

Blennies, feather blennies in particular, are feisty little fishes (as seen in the video). Blennies are a group of small saltwater fishes that remain around relatively shallow water structure, such as oyster reefs and pilings throughout their entire lives. Once they have established a territory, they vigorously defend it and often battle each other in close quarters for food and mates. Productive habitats may house a blenny or mated pair of blennies every couple of square feet, each patrolling their respective property with head up and fins extended ready to scrap. One reason they defend their territory so aggressively is that prime real estate is hard to come by and even harder to get to. These pugnacious little fishes are not strong swimmers, rather they rest upright on their broad pectoral fins and use their broad rearward fins to propel them quickly forward in lightning fast bursts - usually at a trespasser on his territory - and not for long distances.

Striped blennies often lay on their sides inside seashells

There are a few other species of blennies occasionally found in Virginia, but the most common by far are the feather blenny Hypsoblennius hentz, and the striped blenny Chasmodes bosquianus. Though these two are related, the striped blenny is a much less aggressive species and therefore easier to house in an exhibit with other species. They often are found in proximity to each other and a host of other species as well.

Naked gobies can often be found with blennies among oyster shells

Oyster reefs and grass beds are important habitat for a huge variety of similar fish species such as the naked goby, skilletfish (above - pictured stuck on the acrylic with a "suction cup" on its belly) and the much maligned oyster toadfish (a pile of them pictured below)

 Innumerable crabs and shrimps also hide in the nooks and crannies of the oyster shells. 
 Grass shrimp, sometimes called ghost shrimp are an important prey species

All these animals occur in such densities because there is an enormous amount of prey and forage items available in these areas, mainly invertebrates and algae. These structure communities in turn attract a multitude of predatory fishes attracted to a high concentration of prey. Fisherman may not be aware of exactly why oyster reefs draw sea trout, red drum, croaker and stripers, but they certainly know that they do. We attempt to represent these structure-based communities in our "Piling" exhibit that showcases blennies, gobies, skilletfish, sheepshead, scup and a variety of crab species.But as noted earlier the feather blennies rule the tank, nipping at fins and challenging much larger fishes, making it difficult to display more than a dozen or so fishes at a time.

Tuesday, July 9, 2013

Video of "teenage" lined seahorses (H. erectus) feeding

Our "baby" seahorses are growing up. Since they were born several months ago, each of these lined seahorses has grown considerably and they have all begun to take on individual characteristics. As seen in this video, they display a wide variety of colors, patterns and even sizes. Lined seahorses use their colors, elaborate patterning and fleshy appendages to hide amid submerged aquatic vegetation (SAV) which were once much more common and wide-spread throughout the Bay. Micro-communities live in and actually on the leaves of aquatic vegetation - called epiphytes - that support and house a surprising number of small organisms, especially amphipods, and a variety other small invertebrates upon which seahorses feed.
In captivity they are fed enriched P.E. Mysis, live Artemia and Cyclop-Eeze throughout the day.

During the next stage of development these adorable little fishes will begin to mature sexually and we can then finally tell how many males and females were born. Seahorses are sexually dimorphic - males and females are physically different externally - and the male can be discerned by a large leathery brood pouch on the front of his torso. These animals are part of the Line Seahorse SSP (Species Survival Plan). The VLM and many other zoos and aquariums across the country within the AZA community captive breed and exchange lined seahorses to ensure they are genetically diverse and that there will be no need to capture any wild lined seahorses for display. Look for some of the larger juveniles to finally go on public display with the four adults (pictured below) already on display in our seahorse exhibit in the Chesapeake Bay gallery.

Seahorses like to hang around together