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.




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.

The eyes (and telson) have it…..

People are terrified of the horseshoe crab’s telson, or tail.  My reaction is: really? The tail is used to help the horseshoe crab get around in the water, like a rudder on a boat, and they also use it to flip themselves over in the water should they be turned over.  However, it is very difficult for the horseshoe crab to do this on land.  Most of the time they need help, human help, to flip over or risk being eaten by birds and other wildlife.

Another interesting fact I recently learned about the horseshoe crab’s tail: there are photoreceptors on the tail.

What is a photoreceptor?  A photoreceptor is basically a cell that responds to light.

Horseshoe crabs also have 9 eyes and their vision, as we understand it, is very poor. However, they use their eyes and the photoreceptors to navigate their environment.

This gives new meaning to the expression “eyes behind your head”.




Blue Bloods

May begins the month I volunteer at the local Marsh.

Little by little I will share this with you.

Also this month horseshoe crabs begin their mating and egg laying on the shores of the Atlantic and on the beaches of Asia as well.

They frighten a lot of people.  They are living fossils people fear because of the way they look.

Yet they save human lives each and every day.

Have you been to the hospital and/ or had a transplant?  Horseshoe crab blood is used to test for the dreaded Ecoli bacteria on medical equipment and instruments.

Humans have red blood due to the high iron content and horseshoe crabs have blue blood due to high copper content.  They also have a a chemical in their blood called LAL: limulus amebocyte lysate.  LAL is the only (yes, only) chemical on earth, so far, that can be used to test on medical equipment.

Thank a horseshoe crab for helping to save your life or the life of someone you know and for helping to make medical procedures possible.


Ingressus is Latin for “ovation” according to Google Translate.  More quick research shows that it comes from the Latin “ovare” which means to “exult”.

All I can think of are the words ovary and ovum.  Does anyone know of any connections?  I know for instance the prefix “hyster” from where English gets “hysterical”, “hysteria”, and “hysterectomy” are all related to the female gender.  When is a man ever called “hysterical”?  And yes, “hysterical” can be a synonym for “funny” as well.

The most common context is standing ovation, to stand and exult someone or a group of people.

Somehow in English ovation and exult just don’t go together.  In my view of the word, exult is similar to worship or praise, most generally in a religious sense.  Yet as a society we do this with other famous people as well.  To me, ovation is clapping, cheering, whistling.  People show exulting through different vocal means.

Ingressus also makes me think of the game “Ingress” which is similar to Pokemon Go. People use an app to find certain things.  To ingress means going in.