Strawberry Moon

The full strawberry moon is out tonight.  A full moon is always awesome to watch as it rises in the sky every 28 days.

The superstitions surrounding full moons are many yet I find working two or three days after a full moon are usually worse than the full moon itself.

All creatures seem to stir more with a full moon.  The moon tugs at the Earth more than we as humans seem to realize sometimes.

Someone I know has been watching for the horseshoe crabs coming up on shore.  I wonder if the Native Americans watched for them.  In all of the research I’ve done, I’ve never found anything about native Americans and horseshoe crabs.  Are there any stories or legends that have been preserved about them in Native American mythology and oral traditions?  Horseshoe crabs were named so by the colonists due to their shape. What did they think of these creatures as they came up on the beaches?

These are some of the questions I’ve been pondering watching the full moon rise.

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Diamondback Terrapin

One of the students who came to the marsh today found a baby diamondback terrapin. The excitement among the students was quickly contagious.   Some of them had never held a turtle or turtle species before. The baby terrapin was quick to try and get away but everyone held on.

It was tucked in the peat along with the ribbed mussels, fiddler crab burrows, melampus snails, and spartina grass.  We put it back in the water after photos were taken.  The water is the safest place for it as they are easy pickings for seagulls and other birds looking for a quick snack.  We hope it makes it to maturity and adulthood.

Diamondback terrapins can only live in the brackish, mixture of salt and fresh water, that is found in a salt or tidal marsh.  The females make long journeys to lay their eggs.

The marsh where I docent the tours for local school-aged children and their parents and guardians is about 1/3 left of the original size that it once was.  Most of the marsh was taken for a nearby small airport.  The airport has it’s own politics involved.

Most people don’t realize that the females are the larger species of terrapins because they need the larger body to hold their eggs.  They breed with males near the airport and then must undertake a treacherous journey across to very busy roads and what is left of the marsh to lay their eggs in the sandy barrier beach that is next to the marsh.

Many are killed trying to cross one of the roads.  I found a smashed female with her eggs last year on one of them.  If the female makes it across, her eggs and the newborn hatchlings can be eaten by any number of predators including deer, fixes, birds and raccoons while incubating in the nest. Or they bake in the hot sun and pavement.

Their shells need to stay constantly moist.

If you see one, their best bet is to get into the water as quickly as possible.  They are great swimmers and swim long distances.

 

Other Parts

Interior parts of animals are somethings that may be forgotten about.  People go through biology classes to see the interiors, yet do we really think about them?

Do we really realize that all animals have similar organs to ourselves?  Do we stop to think about that?

During my last several posts about horseshoe crabs, I made a list of the body parts I haven’t talked about and usually don’t.

They have: a prosoma (top part), opisthosoma (abdomen), carapace (covering), hinge, chelicera, gnathobase, chilarium, genital operculum, gill opercula, gills, anus, cardiac, extracardiac, and subopthalmic. And I may be missing one or two.

Horseshoe crabs breathe through their gills like fish do yet their gills are on the underside of their bodies.  One can only see them when you pick one up and turn it over. They looked like layered fans.  Their gills allow them to breathe, unlike fish, both in water and on land.

And yes, they have a cardiac system to move that blue blood around.  (See earlier post). One of the main criticisms of their bleeding by pharmaceutical companies is that they insert the needles near the hinge on the horseshoe crab which is also right where their main cardiac is located.  This would be like having a large needle jammed in your neck or chest and your blood sucked out.  We don’t know for sure if they feel pain but they must if they have a brain and neurological system.

Thoughts?

 

 

Mommy and Daddy Crabs

Talking about male/ female crabs and how the horseshoe eggs come to be can be interesting and sometimes awkward depending on the audience.

Unlike the male fiddler crabs that have the large claw to attract females, male horseshoe crabs mate a completely different way.

As mentioned briefly before, females are usually larger and males smaller.  This is the first clue in identification.  If this is not clear, the next best way to identify the crab, if at all possible, is through their legs.

Horseshoe crabs have six sets of legs.  Only the back five are used for them to walk and to eat.  The front set, closest to the top of the shell or carapace, are called pedipalps, palps, or palpi. Pedi comes from the Latin for “foot” and palp from the Latin for “touching”.  On the females, these look like their walking legs.  On the males, they can be described as looking like mittens, boxing gloves, large claws, or large pincers.

Females give off pheromones to attract the males when they, the females, arrive on shore.  The males are usually waiting for the females to come up.

The males use these pedipalps to hold onto the back of the female crab on an area known as the opisthosoma.  This is the back part of the crab right before the telson.  They hang on very tightly.  Waiting.

If you, the reader, ever have the chance to observe the horseshoe crabs mating, watch carefully.  They are silent and strong and follow along with the currents one may or may not be aware of.

More than one male horseshoe crab can follow and fertilize just one female’s eggs.  One female can lay an estimated 9,000 to 90,000 eggs.  She may lay them in one hole or may create more than one hole.  The male or males follow along, attached or not, to fertilize the eggs.

Once the female lays her eggs, the eggs will be on their own.  The female leaves.

Most people find it shocking that the horseshoe crabs would go through all of this trouble and then leave their eggs. Yet if one thinks about it, they are not the only species that do this.  The animals humans look to like frogs, turtles, and fish do this as well.

Not so yummy?

Two common questions I get about animals: what do they eat and how do they eat it?

The horseshoe crab doesn’t have a mandible, or jaw, and neither does it have teeth.  This is fairly common in the non-mammal animals.  Instead, the horseshoe crabs crush their food between their legs before they pass the crushed food into their mouth or gullet. Their mouth or gullet is located at the top of their body.  From there the food is passed to their stomach.

The gullet is also known as a gizzard in bird species.  The purpose of this thick sac with muscular walls, also known as a secondary stomach, is to grind up the food before the food is eaten.

This gullet is important because horseshoe crabs do eat clams and mussels as well as worms, algae, and carrion (dead flesh).  Unlike shorebirds, the horseshoe crabs don’t crack the shells open, they grind the clams and mussels down.  The shells of the clams and mussels are made of calcium carbonate.  Humans cannot each these shells as shells because human teeth aren’t made to grind down thick shells.

Color with Venus and Mars

Would people embrace the horseshoe crab more if it was colorful?

In the world of the seas and oceans, colorful animals have two main purposes.  The first is that color is camouflage and the second is that color warns predators, humans included, of potential toxins and danger.

(Color for land animals also includes mating.)

Horseshoe crabs don’t use color for mating.  Their mating consists of the scent of the female.

Their color is mainly for camouflage on the ocean bottom and the beaches they come up onto to for the females to lay their eggs.

The first time I had a really good look at a mating pair they were highly camouflaged.  I could see the sand along the bottom being stirred up and then what looked like barnacles moving.  When my eyes adjusted, I could then see the larger female with the smaller male attached to her.  Both crabs had barnacles on their shells.

This is common in nature where the female is larger so they have the capacity to hold and carry eggs.  The example of barnacles on their shells is a symbiotic relationship. Two animals exist together but neither, nor a group if relevant, is harmed by the relationship. Barnacle eggs attach to horseshoe crab shells and hitch a ride and grow to maturity.  The crabs are not harmed.

If you could give these creatures a color, what would it be?

CaCO3

CaCo3 + chitin help make up the horseshoe crab’s shell.

(See earlier post for information on chitin.)

People complain that it is tough and hard if they step on one.  These two elements are the reason why.

One question I always ask the students who come is: what are your bones made out of? The sad fact is that the majority do not know.  They  know about the TV commercials telling them to drink milk for strong bones but they don’t know WHAT makes their bones strong.

Calcium is the link between all living creatures that have bones and shells.  Calcium is the fifth most abundant element on earth and has many variations (I’m not getting into more than basic chemistry here).  One of the variations that link us to the horseshoe crabs and all of the other shelled animals like oysters and lobsters is CaCO3, or calcium carbonate.

Calcium carbonate is a calcium compound.  We use it all the time and use products that contain it all the time like toothpaste, vitamins, almond milk, as a calcium supplement, and when we eat dark green vegetables like kale.

Calcium carbonate may have the ability to neutralize acid rain in river water and river ecosystems even though it is not soluble, or dissolves, in water.

CaCO3 is the reason we have fossils of horseshoe crabs going back 450 million years.  It is also the reason their shells are so strong and tough.  It is their home, their refuge, their protection.  CaCO3 is the reason they can travel hundreds of miles through the water and then make it to the shores to lay their eggs.

Calcium carbonate is the reason we get to see them now.