Hidden Gems: Infrequent Sightings

How long do you think it takes to see everything at the National Aquarium? While you will see hundreds of animals during a two- to three-hour visit, there are hidden gems that you might miss—unless you know what to look for.

Shark Eggs!

Of the hundreds of species at the National Aquarium, fewer than three dozen give live birth. Egg-laying is rampant in the animal kingdom, so we see it a lot at the Aquarium.

Some of the stranger eggs you might encounter on a visit are those laid by zebra sharks in Blacktip Reef, and swell sharks and horn sharks in Kelp Forest. The mature females in these exhibits lay them semi-regularly throughout the year, even though no males are present. Without males, the eggs shouldn't be fertile, but Animal Care staff still check them out to make sure. (Swell sharks have been known to store a mate's gametes for years before laying a fertile egg. In rare cases, a female can even lay a fertile egg with her genetic clone inside, a wild mode of reproduction known as parthenogenesis.)

If you spot a tough, leathery-looking pouch in either of these exhibits, congratulations, you've seen a shark egg! Zebra sharks' egg cases are stout and wide, about the size of an adult hand, and are sometimes encased in a veil of yellow mucus that helps secure them to rocks. Swell shark eggs are narrow tubes about 6 inches long that look a bit like flattened, dry corn husks, with curly strings at either end. And horn sharks lay large, spiral-shaped eggs that they can wedge into rock crevices. Aquarium divers remove the cases during regular cleaning or feeding dives, so they're usually only visible on exhibit for a few days.

Babies!

Infertile shark eggs aside, many eggs laid at the Aquarium hatch! In some cases, such as with turtles and skinks in Australia: Wild Extremes, Animal Care staff encourage species to breed, then rear the offspring behind the scenes. Other times, species reproduce freely on exhibit. If you're visiting in spring or summer, you have a better chance at seeing freshly hatched fish in Allegheny Stream, Amazon River Forest, Blacktip Reef and more.

The Elusive Ones

Sure, it's easy to overlook egg cases and minuscule fry. But what about adult animals? Guests who have seen the ornate wobbegong in Blacktip Reef know how easy it can be to miss a full-grown shark. Thanks to camouflage, a natural tendency to hide, or variable activity levels, dozens of species are adept at going unnoticed. Here are some of the Aquarium's lesser-seen residents, found in various Surviving Through Adaptation habitats.

With thousands of animals, it might not be possible to see everything in one go. The Aquarium is open 363 days a year, so there are always more chances to see something new—and with an Aquarium membership, you can enjoy unlimited free admission for a year, plus discounts on behind-the-scenes tours, access to after-hours member events, and much more. So, what will you look for on your next visit?