{"id":1756,"date":"2008-11-30T16:33:36","date_gmt":"2008-11-30T20:33:36","guid":{"rendered":"http:\/\/www.turtlejournal.com\/?p=1756"},"modified":"2008-11-30T20:05:28","modified_gmt":"2008-12-01T00:05:28","slug":"the-large-and-the-small-of-it-whelks","status":"publish","type":"post","link":"https:\/\/www.turtlejournal.com\/?p=1756","title":{"rendered":"The Large and the Small of It (Whelks)"},"content":{"rendered":"

\"\"<\/a><\/p>\n

Knobbed Whelk Captures Large Quahog<\/em><\/strong><\/p>\n

The weather has been\u00c2\u00a0“overcast November” heading into “icy December” in the Great White North.\u00c2\u00a0 While days have been in the low 40s, nights in the mid 20s, winds have been too\u00c2\u00a0feeble and too southerly to bring any cold-stunned turtles onto the beach.\u00c2\u00a0 Those animals that still float about in hypothermic stupor, tossed this way and that by wind and tide, will have to wait until the next strong storm system hits the Cape before they come ashore for rescue.\u00c2\u00a0 In the mean time, we patrol beaches for the odd turtle that might have stumbled onto shore, and we sweep the wrack line for interesting discoveries.\u00c2\u00a0 So, forgive us as we take a brief trip backwards in the Turtle Journal “Time Machine” to the warmth of summer, prompted by whelk egg casings we have\u00c2\u00a0found recently\u00c2\u00a0in Wellfleet Bay.<\/p>\n

<\/embed><\/object><\/p>\n

Click Here to View Video in High Quality<\/a><\/em><\/p>\n

Knobbed Whelk (Busycon carica) in Sippican Harbor<\/em><\/strong><\/p>\n

We\u00c2\u00a0ran across\u00c2\u00a0a mature knobbed whelk (Busycon carica<\/em>) while kayaking in Sippican Harbor for terrapins\u00c2\u00a0during the summer.\u00c2\u00a0 This animal had hunted down a large quahog (Mercenaria mercenaria<\/em>) and held it firmly in the grasp of its powerful foot.\u00c2\u00a0 The whelk was fully engaged in splitting open the bivalve for a delicious dinner.\u00c2\u00a0 As we examined and documented this snail,\u00c2\u00a0it soon became disturbed by our intrusion and dropped its prey to reveal its complete visceral anatomy.<\/p>\n

\"\"<\/a><\/p>\n

Channeled Whelk (Busycotupus canaliculatus)<\/em><\/strong><\/p>\n

The Turtle Journal team has encountered two large whelk species\u00c2\u00a0around Cape Cod:\u00c2\u00a0 knobbed whelks (Busycon carica<\/em>) and channeled whelks (Busycotupus canaliculatus<\/em>).\u00c2\u00a0 \u00c2\u00a0These large (5 to\u00c2\u00a012 inches) predatory sea snails are considered “right-handed” because when held with the spire\u00c2\u00a0up and\u00c2\u00a0siphonal canal\u00c2\u00a0down, the aperture is on the right (dextral) side.\u00c2\u00a0 [NOTE:\u00c2\u00a0 The lightning whelk (Busycon perversum<\/em>, <\/em>found in the south and the Gulf of Mexico) as its name implies is sinistral with the aperture on the left side.]\u00c2\u00a0 Knobbed whelks have tubercles or spines along the shoulder.\u00c2\u00a0 Channeled whelks are slightly smaller than knobbed whelks and have smooth shells with deep square channels that are continuous on all whorls.<\/p>\n

\u00c2\u00a0\"\"<\/a><\/p>\n

Knobbed Whelk (Busycon carica)<\/em><\/strong><\/p>\n

The apperture contains the whelk’s viserca covered by an operculum (horny door) that protects these snails from predators and desiccation.\u00c2\u00a0 Major identifiable body parts include the foot (closest to the operculum), two chemosensory tentacles, two\u00c2\u00a0light sensitive eyes behind the tentacles,\u00c2\u00a0a proboscis between the tentacles with a mouth at the end, and a siphon.<\/p>\n

\"\"<\/a><\/p>\n

Knobbed Whelk Re-Engages with Quahog Prey<\/em><\/strong><\/p>\n

Whelks reside in intertidal and subtidal zones along sandy and muddy bottoms.\u00c2\u00a0 Clam and oyster reefs can be important habitats as these are prey for whelks.\u00c2\u00a0 These snails migrate from shallow\u00c2\u00a0waters in the spring and summer to deeper waters in the winter.\u00c2\u00a0 They will bury into the sand for protection during storms.\u00c2\u00a0 A whelk will\u00c2\u00a0wedge the edge of its shell between the two shells of a bivalve.\u00c2\u00a0 Then, when the two shells are\u00c2\u00a0forced ajar, the whelk\u00c2\u00a0inserts its proboscis and radulla (rasping tongue) into the soft body of the bivalve.<\/p>\n

\"\"<\/a><\/p>\n

Live Horseshoe Crabs (Left) to Bait Whelk Traps (Right) in Buzzards Bay<\/em><\/strong><\/p>\n

The most serious predators\u00c2\u00a0are humans who harvest whelks as a commercial fishery even here in Massachusetts.\u00c2\u00a0 Beyond removing these\u00c2\u00a0graceful, giant gastropods from the seascape, the second tragedy of the whelk fishery is the bait of choice\u00c2\u00a0that is used to attract whelks into traps:\u00c2\u00a0 chopped and quartered horseshoe crabs, live or frozen.\u00c2\u00a0 [Note:\u00c2\u00a0 We will be posting an article on the whelk fishery after the sea turtle rescue season.]\u00c2\u00a0 Europeans are heavy consumers of whelk, which\u00c2\u00a0is sometimes sold as “conch”\u00c2\u00a0and is\u00c2\u00a0also marketed as scungilli for Italians.<\/p>\n

\"\"<\/a><\/p>\n

Chiton<\/em><\/strong><\/p>\n

And now for something really different, as Monty Python might say.\u00c2\u00a0 The critter Don\u00c2\u00a0mentioned in the video clip that the Turtle Journal team had encountered in great numbers on the Reefs<\/a> beach in Southampton, Bermuda is the chiton.\u00c2\u00a0 The photograph\u00c2\u00a0above shows the chiton we found on the knobbed whelk with Sue’s fingernail for size comparison.\u00c2\u00a0 According to Wikipedia<\/a>, chitons are primitive marine mollusks with somewhere between 900 and 1000 existing species\u00c2\u00a0and are sometimes called sea cradles or coat-of-mail shells.\u00c2\u00a0\u00c2\u00a0The chiton shell consists of\u00c2\u00a0eight separate imbricated (overlapping)\u00c2\u00a0plates.<\/p>\n

\"\"<\/a><\/p>\n

Channeled Whelk Casings: Some Opened, Some Plugged<\/em><\/strong><\/p>\n

Whelk mating occurs in spring and fall.\u00c2\u00a0 They are thought to be protandric hermaphrodites, which means that they function first as males when young and smaller, and then whelks change to females as they grow larger and age.\u00c2\u00a0 So, a fishery that targets larger animals, whether through regulation or fancy,\u00c2\u00a0will preferentially\u00c2\u00a0eliminate productive females from the ecosystem.\u00c2\u00a0<\/p>\n

Females produce egg capsules or casings attached to a “string.”\u00c2\u00a0 A string might hold 100 to 120 capsules, with each case containing as many as 35 eggs.\u00c2\u00a0 One end of the string is secured to the bottom of the bay and eggs develop into very tiny whelks within the casings.\u00c2\u00a0 After hatching, small juvenile snails emerge through a predesigned exit hole (see photograph above).\u00c2\u00a0 Most egg casings that wash up on the beach, dredged from the bay floor by nature or man, are empty because the tiny juvenile snails have successfully emerged.<\/p>\n

\u00c2\u00a0<\/p>\n

\"\"<\/a><\/p>\n

\u00c2\u00a0Peterson Field Guides “Atlantic Seahshore” – Kenneth L. Gosner<\/a><\/em><\/strong><\/p>\n

The Peterson Field Guide for Atlantic Seashore offers an excellent diagram of the difference between channeled and knobbed whelk casings.\u00c2\u00a0 Within our area of the coast, the overwhelming number of casings we find are channeled whelks … such as the one that came\u00c2\u00a0from Burton Baker Beach which we will examine in detail below.\u00c2\u00a0<\/p>\n

<\/embed><\/object><\/p>\n

Click Here to View Video in High Quality<\/a><\/em><\/p>\n

Examining Channeled Whelk Plugged Casing<\/em><\/strong><\/p>\n

Most casings that we find on Cape beaches have already hatched; many of the capsules have\u00c2\u00a0opened and presumably the tiny whelks that had developed from the eggs inside the casings have already emerged.\u00c2\u00a0 The chain we found at Burton Baker Beach was different.\u00c2\u00a0 It contained mostly plugged cases and we\u00c2\u00a0selected one of these\u00c2\u00a0plugged casings\u00c2\u00a0that still felt full of fluid for closer examination.\u00c2\u00a0 With a small scissors we snipped the edge along the plugged emergence hole, revealing tiny developing whelk shells inside.<\/p>\n

\"\"<\/a><\/em><\/strong><\/p>\n

Tiny Baby Channeled Whelks<\/em><\/strong><\/p>\n

Little whelks were still suspended in gooey fluid and seemed to be in the process of developing their exterior shells.\u00c2\u00a0 Since most of the casings in this string were still plugged and the whelks had not yet begun to emerge, we assessed that the\u00c2\u00a0tiny whelks\u00c2\u00a0had not yet developed sufficently to survive independently.<\/p>\n

\"\"<\/a><\/em><\/strong><\/p>\n

Channeled Whelk Babies under Microscope<\/em><\/strong><\/p>\n

Under a microscope at low magnification, you can detect individual shell development.\u00c2\u00a0 The one furthest left clearly shows the developing siphon canal at the top.<\/p>\n

\"\"<\/a><\/p>\n

Baby Channeled Whelk for Size Comparison<\/em><\/strong><\/p>\n

The casing pictured above came from a channeled whelk egg chain that the Turtle Journal team collected at Mayo Beach in Wellfleet Bay about four weeks ago.\u00c2\u00a0 While still suspended in mucus-like\u00c2\u00a0fluid, the tiny whelks were further along in their development with more mature shell formation.\u00c2\u00a0 All other casings in this string were empty and presumably tiny whelks had already emerged.\u00c2\u00a0 We include this photograph to give you a better sense of the size of the babies as they begin to emerge as viewed between Don’s index finger (top) and thumb, and to contrast these baby whelks on the cusp of emergence with the ones from Burton Baker Beach that were still developing.<\/p>\n","protected":false},"excerpt":{"rendered":"

Knobbed Whelk Captures Large Quahog The weather has been\u00c2\u00a0“overcast November” heading into “icy December” in the Great White North.\u00c2\u00a0 While days have been in the low 40s, nights in the mid 20s, winds have been too\u00c2\u00a0feeble and too southerly to bring any cold-stunned turtles onto the beach.\u00c2\u00a0 Those animals that still float about in hypothermic […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[824],"tags":[],"_links":{"self":[{"href":"https:\/\/www.turtlejournal.com\/index.php?rest_route=\/wp\/v2\/posts\/1756"}],"collection":[{"href":"https:\/\/www.turtlejournal.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.turtlejournal.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.turtlejournal.com\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.turtlejournal.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1756"}],"version-history":[{"count":19,"href":"https:\/\/www.turtlejournal.com\/index.php?rest_route=\/wp\/v2\/posts\/1756\/revisions"}],"predecessor-version":[{"id":1786,"href":"https:\/\/www.turtlejournal.com\/index.php?rest_route=\/wp\/v2\/posts\/1756\/revisions\/1786"}],"wp:attachment":[{"href":"https:\/\/www.turtlejournal.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1756"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.turtlejournal.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1756"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.turtlejournal.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1756"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}