Mis­un­der­stood mar­vels

Cu­ra­tor calls mu­seum’s skates and rays ‘fas­ci­nat­ing’

Maryland Independent - - News - By SARAH FALLIN sfallin@somd­news.com Twit­ter: @CalRecSARAH

They might not be as cute and cud­dly-look­ing as the star-of-the-show ot­ters at the Calvert Ma­rine Mu­seum, but David Moyer, cu­ra­tor of es­tu­ar­ine bi­ol­ogy, says there is much guests can learn from the mu­seum’s skates and rays.

“I think the most in­ter­est­ing thing … is that peo­ple have mis­un­der­stand­ings of them,” Moyer said.

The skates and rays are the first liv­ing crea­tures vis­i­tors to the ma­rine mu­seum en­counter by way of an ex­hibit with a large round pool in the cen­ter. The ex­hibit started out as a tem­po­rary one a decade or so ago, but the crea­tures were so pop­u­lar that the ex­hibit, called “The se­crets of the mer­maid’s purse,” be­came per­ma­nent, Moyer said.

Vis­i­tors get the chance to in­ter­act and touch the skates and rays from time to time, un­like the other crit­ters who live at the mu­seum. How­ever, a trained per­son has to be man­ning the ex­hibit for this to oc­cur. Dur­ing the rest of the time, vis­i­tors should obey the “don’t touch” sig­nage.

“They’re just fas­ci­nat­ing to watch,” Moyer said.

Skates and rays look alike and are man­aged very sim­i­larly, but have some key dif­fer­ences. First of all, skates lay eggs, while rays give birth to their young. The egg cas­ings laid by skates are called mer­maid’s purses and can com­monly be found while beach-comb­ing, even along the Ch­e­sa­peake Bay.

Skate ba­bies take eight to 12 weeks to de­velop and hatch, and staff at the Calvert Ma­rine Mu­seum can shine a light on the mer­maid’s purses to see how the young skate in­side each one is de­vel­op­ing. To do the same for a ray, an ul­tra­sound would be re­quired. Next to the large round tank where the adult skates and rays swim, there’s a smaller tank con­tain­ing mer­maid’s purses as well as some young skates, so all stages of the skate’s life cy­cle are on dis­play at once.

An­other big dif­fer­ence be­tween skates and rays is that only the rays have the abil­ity to sting, which tends to give them a bad rep­u­ta­tion, es­pe­cially after a large species of ray killed the “Crocodile Hunter” Steve Ir­win.

But rays will only sting when threat­ened. Most sting­ing in­ci­dents hap­pen when hu­mans ac­ci­den­tally step on rays that are hang­ing out on the bot­tom. While a jel­ly­fish sting is a sur­face sting on the skin, the sting­ing of a ray is from a sharp barb that breaks the skin and causes in­ter­nal dam­age.

The rays at the Calvert Ma­rine Mu­seum pe­ri­od­i­cally get their barbs trimmed, as they’re made of a fin­ger­nail-like ma­te­rial. Trim­ming the sharp tip of the barb means it can’t eas­ily break skin. Through­out their lives, rays will grow mul­ti­ple stingers and shed them.

The mis­con­cep­tions of the rays ex­tend be­yond the stingers. Moyer said oys­ter­men tend to think cownose rays are prob­lem­atic, but the rea­son be­hind the prob­lem is that other peo­ple are killing sharks, which are the main preda­tors of cownose rays. In re­cent years, cownose ray hunt­ing con­tests have been at the cen­ter of con­tro­versy.

To re­store the shark pop­u­la­tion to a state where the ray pop­u­la­tion gets back un­der con­trol would take about 30 years, Moyer said.

“The prob­lem is not the cownose rays, the prob­lem is hu­mans … tak­ing out top level preda­tors … The re­al­ity is, we are the prob­lem. We’ve dis­rupted the food web and we get mad,” Moyer said.

STAFF PHO­TOS BY SARAH FALLIN

Above, a ray swims along in the main ex­hibit tank at the Calvert Ma­rine Mu­seum. Be­low, skates lay eggs in “mer­maid’s purses,” pic­tured here, while rays give birth to their young.

Skates lay eggs in “mer­maid’s purses,” pic­tured here, while rays give birth to their young.

A smaller view­ing tank al­lows vis­i­tors to see un­hatched mer­maid’s purses as well as young baby skates.

David Moyer, cu­ra­tor of es­tu­ar­ine bi­ol­ogy at the Calvert Ma­rine Mu­seum, watches skates and rays in the ex­hibit tank.

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