Limulus

Limulus

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The living FOSSIL
limulus polyphemus

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Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Merostomata
Order: Xiphosura
Family: Limulidae
Genus: Limulus
Species: L. polyphemus
Scientific classification

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Nomenclatur
e
#Limulus: (odd)
it was thought
to have only
one eye.
Horseshoe
King crab:
protect crabs
Big brown

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Evolution
•The Limulus is a "living fossil“
• NOchange in the last 445 million
yearsold.
•origin dates back to Triassic times,
over 200 million years ago, a time
when the first dinosaurs and
primitive mammals appeared .

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Limulus can
reach maturity
in nine to 11
years
Maturity

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Habitat
•Limulus is found along the
Atlantic coast .
•spending summers in the
shallow coastal waters.


•winters offshore in the mud.

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migration
•main area of
annual
migration is
Delaware Bay
(The male is smaller
than the female.) when
female goes ashore to
lay her 200-300 dark
greenish eggs in a
depression in the sand.
The males then release
sperm which fertilize
the eggs.
Red Knot eats the eggs

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Mouth
•Mouth shifted to be
between legs
(Merostomata).
•He uses his
specialized strong
front legs
(gnathobase) to
accomplish this
grasping .

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feeding
feeding on sea worms
and young clams

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Breathing
•By gill books do much the same
things as lungs.

•Five in number, each gill book
contains 100 "leaves"
•The total surface area is large
enough to permit the exchange
of oxygen and carbon dioxide.

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•the gill books can sometimes be used
by the animal as paddles while
swimming upside down in the water .
•it also allow them to breathe
underwater .
•also allow them to breathe on land for
short periods of time

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Carapace & molting
•Because Limulus has a
hard outer shell (called an
exoskeleton) .
•it has to shed (molt) its
shell periodically in order
to grow.
•Many of the "dead" Limuli
you find on
The beach is not dead, but
the castoff shells of
molted Limuli

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•Once a Limulus sheds its old shell, it
has a new, soft one that hardens
In about 12 hours.
**it leaves exuvium back in
contract to other animals.

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Tail
•Tail is not a weapon.
•If horseshoe crabs get turned
on their back in the surf and get
stranded on the beach, they use
their long tail to turn over. If
they cannot get turned back
over they die.

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Eye
•Limulus has four eyes - two small,
simple eyes up forward and two larger,
compound eyes (much like a fly's
eyes) on either side of the shell.

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Eye Research
•Much of what we know about the
function of our eyes is the result of
studies that began over 50 years ago
on the large, compound eyes of the
horseshoe crab.
•Its eyes have a relatively simple
construction, and the optic nerve is
readily accessible.
•it is easy to keep Limulus alive in the
laboratory, making it an ideal animal
for eye research.

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•In 1967, Dr. H. Keffer Hartline
received the Nobel Prize for his research on
horseshoe crab vision.
He discovered how sensory cells in the
retina help the brain process visual cues,
enabling horseshoe crabs to see
lines, shapes, and borders.
This mechanism, called lateral inhibition,
allows horseshoe crabs to distinguish
mates in murky water.

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Research of this type is helpful
to :
•understanding human eye diseases
like retinitis pigmentosa, which
causes tunnel vision and can lead to
total blindness

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Chitin Research
•horseshoe crabs have a hard outer shell,
or exoskeleton, that provides protection
from predators.
• Millions of tightly interwoven strands of a
cellulose-like material called chitin serve
as a tough and flexible glue that holds
together the shell .
•The chitin in horseshoe crabs is favored
for research over that found in other
arthropods because it is very pure. Chitin
is natural, non-toxic, non-allergenic, anti-
microbial.

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Check Out the Many Uses of
Chitin!
•chitin had wound-healing which
enhanced healing time by 35 to 50%.
•make dressings for burns which
accelerate healing and reduce pain
•anti-bacterial sponges.
• contact lenses , tumor inhibition,
blood cholesterol control, and
tampons.

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when chitin is heated with a chemical
solution called Chitosan that has
some advantages over chitin because
* it is more water-soluble.
•good for cleaning up toxic organic
compounds.
•can bind with fat, acting like a
sponge in the digestive tract. without
ever entering the bloodstream .
•Seeds treated with chitosan are
larger and stronger and more
resistant to fungal diseases .

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limulus Blood
•Human blood is red because it has a
red pigment called hemoglobin which
contains iron. The Limulus blood
pigment hemocyanin contains copper
so it has blue color .

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LAL Research
•Limulus amoebocyte lysate.
• It's a very sensible system.
• Seawater comes into contact with the tissue and
bacteria come into contact with the blood and
• begin to enter (i.e. infect) the body of limulus.
•small bits of the cell wall slough off as the
bacteria propels itself through the blood.
•Limulus blood cells detects this tiny fragment and
responds by releasing the contents of the
granules into the surround medium.
•These granules contain a clotting factor
• called coagulogen .

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coagulog
en

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One liter of LAL
is worth $15,000 !

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LAL applications
•in the initial management of peritoneal
dialysis patients with peritonitis .
•Sterile medical equipments.
•Can detect and kill bacteria, virus .
•LAL early diagnosis for
• leukemia.
•Anemia.
•Mental disorders in babies.
•Meningitis.
•Vitamin deficiency.

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