1. Limulus polyphemus “The creature that crawled out of the past!”
Horseshoe Crab
Limulus polyphemus
“The creature that crawled out of the past!”

2. Horseshoe Crab Distribution
most popular area for the horseshoe crabs is in the Delaware Bay

3. Spawning Habitat Shorebirds feasting on horseshoe crab eggs
Eggs need - porous,
well-oxygenated sediments
In 1995, B95 was tagged and estimated to be close to 20 years old. Dubbed "Moonbird" because the total number of miles this red knot has traveled during its lifetime is equivalent of the distance to the moon and halfway back.
Shorebirds feasting on horseshoe crab eggs

4. Nursery Habitat Within bays and coves, next to sandy beaches
The water is shallow, food is sufficient, and has their preferred salinity of the water around
5 ppt (parts per thousand). 

5. FACT Among the world’s oldest creatures
How long have they been on this planet?
540 million years ago to the present
Before human civilization
Before the dinosaurs
Before flowering plants
During the era in our planet's history when visible life first appeared (one celled organisms)
Toward the end of the Cenozoic Era, beginning with the Holocene (11,000 BC to the Present), we look specifically at the evolution and development of the Delaware Bay.

6. FACT 4 known species in the world
Only 1 species found along the Delaware coastline (range from Maine to the Yucatan Peninsula)
LARGEST concentration in the world is found in the Delaware Bay
It is not really a crab!
What is the horseshoe crab closely related too?
Spiders and scorpions (arthropod, arachnids)
How many pairs of claws does a horseshoe crab have?
5 pairs
True crabs have ONLY one pair of claws
They also lack antennae and mandibles like true crabs
Like a spider, horsecrabs have 2 claws located in front of their mouth

7. FACT When is the BEST time to see horseshoe crabs?
Last spring (May) when the come ashore to spawn
Which is larger in size, the male or the female?
FEMALE
She deposits on an average 4,000 eggs in nests along the shore line
Horseshoe eggs serve a great food source for which animals?
MIGRATING shore birds
Which shore bird’s life depends on the horseshoe crab eggs?

8. Red Knot Star of the Show!! A MOST amazing athlete
It can out-eat, out-race, out-distance, and out-perform any one of YOU or any human at every turn!

9. Rufa Red Knot Calidris canutus rufa
one of the longest distance migrants in the animal kingdom.
Wingspan of 20 inches, 9 inch length (size of robin)
This bird flies more than 18,000 miles each year between breeding grounds and wintering grounds
In just a few days, the birds nearly doubles their weight with eggs
December 2014, the U.S. Fish and Wildlife Service announced federal protection for the rufa red knot
Designating it as threatened under the Endangered Species Act.

10. This tiny tracking device fitted to the red knot contained a clock, a microprocessor, and a battery

12. Horseshoe Crab Taxonomy
Kingdom: Animalia
Phylum: Arthropoda — joint-legged animals
Subphylum: Cheilcerata — animals with no jaws
Class: Merostomata — mouth surrounded by legs
Subclass: Xiphosura — from the Greek Xiphos meaning sword and ura meaning tail
Order: Xiphosurida — sword-tailed animals
Family: Limulidae — one living member, Limulus
Genus: Limulus — from the Latin, meaning somewhat oblique, odd, or askew and referring to the sideways placement of the compound eyes
Species: polyphemus — from the Greek, meaning one-eyed giant and referring to the simple eyes on the front of the shell

13. Anatomy
What is the top view of the shell of the horseshoe crab called?
Dorsal
What name was the horseshoe crab first called?
Horse foot
What the bottom view of the shell called?
Ventral

16. Male Horseshoe Crab

17. horseshoe crab in the process of molting

18. Male vs Female

19. horseshoe crabs shell

20. one of the compound eyes of a horseshoe crab

21. the hinge that joins the cephalothorax and opisthosoma.

22. a horseshoe crabs anus

23. Super close-up photo of a horseshoe crabs chelicerae

24. how a horseshoe crab can curl up for protection

26. open gills of a horseshoe crab

27. the book gills and flap cover genitalia of a horseshoe crab

28. male horseshoe crab upside down

29. movable spines of a horseshoe crab

30. the horseshoe crabs chelicerai (front pincers)

31. underside of a male horseshoe crab with barnacles

33. the mouth of a horseshoe crab

34. male horseshoe crabs mouth

35. front claws of a male horseshoe crab

36. male horseshoe crabs front leg

37. male horseshoe crabs pusher leg

38. male horseshoe crab close-up

39. a female horseshoe crabs underside

40. a female horseshoe crab flaps covering genitalia

41. Horseshoe crabs serve an important role in the bay ecosystem
How?

42. They feed at night, primarily on mollusks, crustaceans and worms on the ocean floor
Their eggs are an important food source for at least 11 species of migratory shore birds
Including the red knot
Sea turtles also eat the eggs and larvae.
Eggs are important for the shoreline ecosystem
Adult horseshoe crabs are preyed upon by sharks, sea turtles, gulls
Humans for use them as bait or fertilizer

43. How Horseshoe Crab Blood Saves Millions Of Lives
Crash: A Tale of Two Species (PBS)
(3:16)

45. Frederick Bang
In the 1950’s discovered that the blood of horseshoe crabs contained a clotting agent that when it comes in contact with certain types of bacteria it clots the blood and forms a gel that surrounds the bacteria.
This allows for the bodies antibodies to take care of the bacteria.
Bang and an associate created Limulus amoebocyte lysate or LAL which is now used to test for certain types of bacteria.
Horseshoe crabs are captured and after they are inspected, blood is carefully bled.
The procedure does not usually harm the horseshoe crabs and death rates are very low.
One quart of LAL sells for $15,000.

46. How Horseshoe Crab Blood Works
Blood has remarkable antibacterial properties
Crab blood is bright blue
It is copper-based hemocyanin to transport oxygen where vertebrates (including humans) use iron in hemoglobin
Many invertebrates have amebocytes instead of white blood cells to fight infection
Horseshoe crab amebocytes coagulate around as little as one part in a trillion of bacterial contamination
Unfortunately, overharvesting in North America has led to a decline in crab populations

47. How are horseshoe crabs useful to people?
Food source for the Native Americans
Shell used to scoop water
Tails used as tips for fishing spears
Fertilizer for crops

48. What is chitin? Ki – tin)
A substance that makes up the horseshoe crab shell
How is it used?
Surgical sutures and bandages that promote healing
How is Lysate (li-sate), a chemical found in horseshoe crab blood useful to human?
It is used to diagnose contaminants in prescription drugs

49. Make your Horseshoe Crab Model
When done, answer the puzzle questions

50. Horseshoe Crab Model
Can you locate the compound eyes?
Is your crab model a male or a female?
Female
Explain how you can tell

51. Quiz Time

54. Where (and when) do horseshoe crabs evolve?
The evolution of the horseshoe crab extends back far before the dawn of human civilization, before the dinosaurs, before flowering plants... back to the era in our planet's history when visible life first appeared.
from the Paleozoic Era and provides an overview of the changes to our planet's geology, climate, flora and fauna from 540 million years ago to the present.
Toward the end of the Cenozoic Era, beginning with the Holocene (11,000 BC to the Present), we look specifically at the evolution and development of the Delaware Bay.

55. Horseshoe Crab Taxonomy
Kingdom: Animalia
Phylum: Arthropoda — joint-legged animals
Subphylum: Cheilcerata — animals with no jaws
Class: Merostomata — mouth surrounded by legs
Subclass: Xiphosura — from the Greek Xiphos meaning sword and ura meaning tail
Order: Xiphosurida — sword-tailed animals
Family: Limulidae — one living member, Limulus
Genus: Limulus — from the Latin, meaning somewhat oblique, odd, or askew and referring to the sideways placement of the compound eyes
Species: polyphemus — from the Greek, meaning one-eyed giant and referring to the simple eyes on the front of the shell

58. Male Horseshoe Crab

59. horseshoe crab in the process of molting

60. The Horseshoe Crab (also known as the King Crab)
a hard-shelled invertebrate that lives in warm, shallow coastal waters on the sea floor.
It is not really a crab;
it is more closely related to arachnids (spiders and scorpions).
first appeared about 500 million years ago (during the Ordovician Period), and has changed very little since.
There are four species of Horseshoe Crabs alive today;
they live off the coasts of India, Japan, Indonesia, the eastern USA, and the Gulf of Mexico.

61. Diet: eats sea worms and mollusks (like young clams)
Diet: eats sea worms and mollusks (like young clams). They find their prey while walking along the sea bed; they are predominantly nocturnal (most active at night).
Reproduction: hatch from eggs that the female lays. She lays roughly 20,000 small, green eggs in holes that she digs in the sand on the beach.

62. Anatomy a hard outer shell (an exoskeleton),
5 pairs of jointed legs and a pair of pincers.
The Horseshoe Crab is up to 2 ft (60 cm) long and weighs up to 10 pounds (4.5 kg);
it molts its skin many times as it grows.
The male is two-thirds the size of the female.
The long tail is not a weapon; it is used as a rudder (for steering) and for righting itself when it is flipped upside down.
The Horseshoe Crab has light blue, copper-based blood.
It breathes using book gills, thin plates located on the abdomen.

63. have 5 sets of leg like appendages that are used for mobility and to direct food into it’s mouth. The horseshoe crab doesn’t have a jaw. What it does is direct food into it’s mouth where the food is ground up by it’s gizzard which contains sand and small bits of gravel to help with the process

64. Long ago humans realized that horseshoe crabs could be useful in their everyday living.
Native Americans used the shells of horseshoe crabs as tools and the tails as spear tips.
They also discovered that the horseshoe crabs made good fertilizer as their bodies were high in Nitrogen.
This knowledge was later passed on to the European settlers and was used up into the late 1900’s.
More recently, scientists in the medical field have started to study the horseshoe crab for medical reasons.
Research on the compound eyes of the horseshoe crab has lead to a greater understanding of how our own eyes work.

65. Frederick Bang
In the 1950’s discovered that the blood of horseshoe crabs contained a clotting agent that when it comes in contact with certain types of bacteria it clots the blood and forms a gel that surrounds the bacteria.
This allows for the bodies antibodies to take care of the bacteria.
Bang and an associate created Limulus amoebocyte lysate or LAL which is now used to test for certain types of bacteria.
Horseshoe crabs are captured and after they are inspected, blood is carefully bled.
The procedure does not usually harm the horseshoe crabs and death rates are very low.
One quart of LAL sells for $15,000.

66. horseshoe crabs shell

67. one of the compound eyes of a horseshoe crab

68. the hinge that joins the cephalothorax and opisthosoma.

69. a horseshoe crabs anus

70. Super close-up photo of a horseshoe crabs chelicerae

71. how a horseshoe crab can curl up for protection

73. open gills of a horseshoe crab

74. the book gills and flap cover genitalia of a horseshoe crab

75. male horseshoe crab upside down

76. movable spines of a horseshoe crab

77. the horseshoe crabs chelicerai (front pincers)

78. underside of a male horseshoe crab with barnacles

80. the mouth of a horseshoe crab

81. male horseshoe crabs mouth

82. front claws of a male horseshoe crab

83. male horseshoe crabs front leg

84. male horseshoe crabs pusher leg

85. male horseshoe crab close-up

86. a female horseshoe crabs underside

87. a female horseshoe crab flaps covering genitalia