Archive for the ‘Marine Species’ Category

Juvenile “Blue Bloods” Emerge

Tuesday, April 29th, 2014

Sue Wieber Nourse Examines Two Juvenile Horseshoe Crabs

Juvenile horseshoe crabs rocked Outer Cape salt marsh creeks during the April 28th flood tide.  Turtle Journal celebrates the emergence of these true “blue bloods” each spring.  We have been checking for their awakening since late March, but this year’s cold spring temperatures have prolonged their winter slumber.  (See Salt Marsh Awakening: Juvenile Horseshoe Crabs Active on Outer Cape, April 18th, 2013 and Mid-March Emergence of Juvenile Horseshoe Crabs, March 19th, 2012.)

Two Juvenile Horseshoe Crabs (Limulus polyphemus)

Admittedly, the horseshoe crabs we discovered this morning were a bit sluggish in today’s chilly water temperatures, under cloudy skies and with a stiff northeast ocean breeze.  Today’s specimens ranged in weight from a little over 1/2 ounce (17 grams) to 4 1/3 ounces (122 grams).  The horseshoe crab’s exoskeleton (shell) does not expand.  To grow, horseshoe crabs molt, as many as five times in the first year, three in the second, two in the third, and once a year thereafter until maturity is achieved.  It takes sixteen and seventeen molts respectively over a period of nine to eleven years for a male and female horseshoe crab to reach maturity.

Tiny 1/2 Ounce Juvenile Horseshoe Crab (Limulus polyphemus)

Ventral View of Juvenile Horseshoe Crab (Limulus polyphemus)

Measuring Tiny Juvenile Horseshoe Crab (Limulus polyphemus)

The tiniest horseshoe crab measured less than 2 1/4 inches (~ 6 centimeters) long (minus its tail/telson).  As you may know, horseshoe crabs are the true “blue bloods” of the animal kingdom with blood composed of copper rather than iron.  This limulus blood yields a unique and powerful gram-negative bacterial detector that saves human lives.  Horseshoe crabs have also been extremely valuable in the research of vision with both compound and simple eyes, as well as facilitating many other scientific and medical breakthroughs.

Larger (4 1/3 Ounce) Juvenile Horseshoe Crab

Ventral View of 4 1/3 Ounce Juvenile Horseshoe Crab

The largest juvenile horseshoe crab we encountered this morning measured about three times the length of the smallest and hit the scales at 4 1/3 ounces.  The ventral (bottom) view of this juvenile horseshoe crab clearly shows the five walking legs on each side, the forward feeding pincers (Chelicerae), and the rear book gills.   The telson (tail spine) is pointed directly at the camera.

Juvenile Horseshoe Crab (Limulus polyphemus)

Juvenile horseshoe crabs are delightful to watch as they plow through the sandy bottom of creek channels.  As adults, horseshoe crabs are Nature’s auto-tillers, constantly refreshing coastal tidal and inter-tidal flats.  Appearing as ancient as the earliest trilobites, horseshoe crabs stir awe in the Turtle Journal team.  Sadly, humans have harvested these valuable critters to the edge of extinction, extirpating them from one estuary after another, impoverishing our entire tidal and inter-tidal eco-systems, and driving shorebirds that survive epic migrations on nourishing horseshoe crab eggs to the brink, as well.  So, it is especially joyful each spring to find juvenile horseshoe crabs as we continue to hope for sanity to prevail among state and federal wildlife managers of this important foundational marine species.

Hyper Active Horseshoe Crab Nursery

Thursday, May 9th, 2013

Don Lewis Studies Two Tiny Juvenile Horseshoe Crabs

The Turtle Journal team revisited our “secret” horseshoe crab nursery on Thursday afternoon.  We last checked this spot on April 18th; see Salt Marsh Awakening: Juvenile Horseshoe Crabs Active on Outer Cape Cod. 

Rufus Examines Tiny Juvenile Horseshoe Crab

We wanted to get a sense of how well these ancient creatures may be doing, particularly in this long, chilly Spring.  In the decade we have been checking this location each Spring for juvenile horseshoe crabs, we have never before seen so much activity.

Three Tiny Juvenile Horseshoe Crabs

Dozens of juvenile crabs from tiny to small to mid size bounced around the salt marsh tidal pool like Tonka Toy bulldozers plowing through a playground sandbox.

Juvenile Horseshoe Crabs Bulldoze Serpentine Mazes

We can only laugh at their antics as they carve serpentine mazes in the oozy bottom.  Adult horseshoe crabs are beneficial auto-tillers of tidal and subtidal zones, a skill they obviously seem to practice from birth.

Juvenile Horseshoe Crab Left Compound Eye

The exceptional compound eyes of horseshoe crabs never cease to amaze us.  Much of our knowledge about human eyesight came from studies of these compound eyes.  Dr. H. Keffer Hartline received the Nobel Prize for his research on horseshoe crab vision in 1967.

Two Tiny Juvenile Horseshoe Crabs in Nursery

While documenting the science of this horsehoe crab nursery is rewarding per se, we confess that watching these juveniles spin around the tidal pool like pre-teens driving their first amusement park bumper cars can be mesmerizingly delightful.  So much so that you forget that you’re even doing science.

Horseshoe Crab Spawning Begins on Massachusetts SouthCoast

Wednesday, May 8th, 2013

Rufus Discovers First Spawning Horseshoe Crabs

The Turtle Journal team patrols SouthCoast beaches each morning throughout the Spring season.  This morning, as Sue Wieber Nourse and Rufus the Turtle Dog walked a Buzzards Bay barrier beach, they spotted pairs of spawning horseshoe crabs scatter along the shoreline in the morning high tide. 

Spawning Horseshoe Crab Pair (Female in Front)

This morning’s ~ 7:30 am high tide brought the first evidence of spawning horseshoe crabs this season.  The pair above well illustrates a spawning pair.  The larger female is in front with the smaller male grasping onto her shell, so that he can be Johnnie-on-the-spot when she deposits her eggs along the tide line.

Spawning Horseshoe Crabs on SouthCoast Barrier Beach

Sue has been observing these SouthCoast barrier beaches for many years now as principal of Turtle Journal and formerly as director of Tabor Academy’s Marine Science Center and as inaugural holder of the Jaeger Chair for Marine Studies.  She reports that today’s spawning burst, while only containing a handful of crabs, still represents the largest number of specimens she has yet seen in this location.  Horseshoe crabs had nearly been extirpated on the SouthCoast by harvesters who chop them up for cheap whelk bait.

Turtle Journal Discovers Stranded Electric Torpedo Ray at Fisher Beach in Truro

Tuesday, January 8th, 2013

 Rufus Guards Stranded Torpedo Ray in Truro

With a southwest breeze blowing across the bay, Turtle Journal’s Sue Wieber Nourse and Rufus the Turtle Dog drove out to Truro on Outer Cape Cod to see what might have been pushed ashore with the morning’s 11.5-foot tide.  In the bright sunlight, they patrolled Duck Harbor in Wellfleet and Ryder in South Truro with great joy, but few discoveries. 

Female (Electric) Torpedo Ray at Fisher Beach in Truro

Then, an eighth of a mile north of the landing at Fisher, they encountered a female electric Torpedo Ray that had washed ashore.  Turtle Journal has found torpedo rays stranded along the Cape’s bayside beaches in the fall as we search for cold-stunned sea turtles.  (See Shocking Discovery!  Torpedo Ray in Wellfleet Bay.)  Torpedo rays have anterior organs that can generate and discharge 220 volts to stun a prey … and to keep predators like human researchers at a respectful distance.

Section from Left Electrical Organ of Large Torpedo Ray

The torpedo ray has two kidney-shaped electrical organs that make up 20% of its weight and are located on the pectoral fins. They generate a power equivalent to 220 volts that stuns prey with a burst of electric current. Its prey includes flounder, silver hake fish, small sharks such as dogfish, eels, worms and crustaceans. After stunning its prey, the torpedo ray guides food with its pectoral fins toward its protruding mouth for ingestion.

Rough Field Measurements of Torpedo Ray in Truro

Without a full scientific kit on hand, Sue managed with the tools we wear on our feet for a rough field measurement of specimens.  This female measured approximately four feet long and three feet wide, and seemed in relatively good shape.  Turtle Journal informed the Wellfleet Bay Wildlife Sanctuary of the specimen’s location, so that a follow-up necropsy could document the specimen and possibly determine its cause of death.

Great Blue Heron Chicks Hatch @ Marion Rookery

Tuesday, May 22nd, 2012

Great Blue Heron Chicks Hatch in Marion Rookery

Turtle Journal has monitored the Great Blue Heron rookery in Marion on the SouthCoast of Massachusetts since early April.  See Great Blue Heron Rookery on Massachusetts South Coast.  This afternoon, in relentless rain and dense mist, Sue Wieber Nourse spotted hatched chicks in two adjacent heron nests.  The babies were noisy and demanding; the adults patient and providing.

Great Blue Heron Hatchlings

After a period of intense feeding, the chicks settled down for a bit and the adults spent a few moments grooming.  But with insistent babies in the nest, nothing lasts for long and the chicks soon were pleading again for attention.  While Don acknowledges that his video is a bit shaky due to extreme distance from the nest and terrible weather conditions, the clip does provide a good sense of the chicks’ early days.

Adult Great Blue Heron Presents Small Fish to Chicks

As Turtle Journal observed these two nests today, we discovered that the adult would occasionally offer small fish to the chicks by waving it from its beak and then laying it next to the babies in the nest.  The team will continue to monitor these hatchlings in the days ahead … hopefully under some bright sunshine for a better set of documentary pictures and clips.