Good morning! In this episode, I would like to share with you biological data on the Atlantic horseshoe crabs.
And it is one of the most interesting species whose development we had a chance to observe in the Gdynia Aquarium.
I am taking you to the Northeast coast of the United States of America where the genus Limulus lives today.
You'll meet horseshoe crabs from Maine to Florida, with peak numbers in Delaware Bay
and in the Gulf of Mexico as far as the Yucatan Peninsula in Mexico.
What's fascinating about horseshoe crabs is that they have existed almost unchanged for 450 million years in the ocean.
These ancient animals have survived mass extinctions, space catastrophes, glacial periods...
but most of all, horseshoe crabs can be fascinating by their amazing appearance.
Its intricately constructed body, equipped with numerous legs, is made of three main parts.
This is the head area, the body area, and the tail, which functions as a rudder underwater.
The whole thing is covered with armor that looks like a horseshoe.
Thus, the name.
Another Polish name "mieczogon" comes from the long spike - telson, which is located at the end of the carapace.
The horseshoe crab belongs to the carnivorous Merostomata.
The horseshoe crab diet is based on algae, polychaetes, molluscs,
that is, everything that this animal is able to find by combing the seabed.
The horseshoe crab has no jaws, it crushes the food it catches and then pushes the pulp into its mouth.
The processing of such food - the further one - takes place in the stomach, which contains gravel and sand.
In breeding, it happens that we provide horseshoe crabs with food of sinking granules.
It is interesting that horseshoe crabs have 9 eyes, thanks to which they can see well under water even in the dark.
It is easiest to locate the large compound eyes, which are located on either side of the head.
They provide monochromatic vision, which means that the horseshoe crab sees the world in black and white.
Horse crabs breed under the cover of night, during the full moon.
Compared to other groups of invertebrates, it is an animal that reaches sexual maturity very slowly.
The maximum recorded lifespan of horseshoe crabs is 20 years.
About halfway through their lives, these organisms reach sexual maturity.
The males are the first to start their migration to spawn.
When they meet a female on their route, they stick to her body, to her carapace, with special walking legs,
which are equipped with claws.
In general, these legs look a bit like boxing gloves.
Such a male can be glued to the female's carapace even for several months.
When the females reach the beach, they lay in a hole on the beach, in such sand, up to 60,000. eggs.
The eggs initially hatch into larvae that float in shallow layers of water.
During puberty, we can observe phenomenon known as "moulting", i.e. getting rid of too small carapace,
17 times.
Females are much larger than males.
The largest individuals, the largest specimens, are about 60 cm,
while their weight can reach up to two kilograms.
The life of many species depends on the number and condition of horseshoe crabs.
They look a bit like such a living open-air museum,
Often the horseshoe crab carapace is colonized by a large number of different species,
we can see barnacles on it, we can see various algae or bryozoa on it.
The horseshoe crab or its eggs are food for many groups of animals.
for fish, for various species of sea turtles or alligators, as well as for numerous migrating birds.
Various factors contribute to the significant decline in the population,
here we can mention the overfishing of horseshoe crabs as bait for fish,
a very large proportion of the population, roughly 10% of the breeding population
dies as a result of the rough waves rolling such a horseshoe crab onto its back,
and then he needs human help.
Thanks to its extraordinary properties, the milky blue blood of horseshoe crabs is used in the biomedical industry.
A liter of such blood costs 15,000 US dollars on the market.
The procedure is such that horseshoe crabs are taken from the wild,
1/3 of their blood volume is drained in the laboratory,
however, after the whole procedure, pharmaceutical companies are obliged to return such an organism back to the natural environment.
Blood volume should return to normal within a week
and most such horseshoe crabs have a good chance of survival.
A lasting legacy in horseshoe crab research was left by two American scientists,
Fred Bang i Jack Levin.
They were the first to notice that horseshoe crabs hemolymph in the presence of bacterial endotoxins,
Produces defense aggregates visible to the naked eye.
Soon after, they developed a test that the Food and Drug Administration
allowed in 1977 to control the microbiological purity of drugs, infusion fluids, endoprostheses, pacemakers and vaccines.
This test has never failed. It can be said that most people on Earth owe their lives to the horseshoe crab.
The hope for horseshoe crabs is to start using a synthetic alternative known as recombinant factor C,
which is equivalent to horseshoe crab hemolymph.