Published on

Published in: Education, Technology
  • Be the first to comment

  • Be the first to like this

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide


  1. 1. MEROSTOMATA (Horseshoe Crabs) By Jamie Forysth Pd. 6/7 MEROSTOMATA IS : A mostly extinct class of Arthropods (class: arthropoda). They are in the kingdom of animalia and the domain of eukaryotes. Where did they come from? part is the abdomen it is where the Horseshoe crabs evolved out of the gills are attached. The last part is the Paleozoic era along with trilobites. telson or tail. It is used to steer in They have been unchanged for water and flip its self over if needed. nearly 400 million years. They are T r a n s p o r t a t i o n distantly related to spiders. They For there external transportation mature at age nine and are able to most horseshoe crabs have four legs live for thirty years. that end in pincers. Males have large W h a t d o t h e y l o o k l i k e ? claws on their two front legs. Their T h e y a r e p r o t e c t e d b y a n internal transportation is when it exoskeleton mad up of three parts: eats its food it is broken down in the Above is the underside of a the Carapace, Abdomen, and the gizzard. Then enzymes are secreted horseshoe crab. You can see the legs, the mouth, and the start telson. The Carapace is first it into a stomach-intestine by an organ of the book gills. contains the eyes, legs, pincers, called hepatopancreas. mouth, brain, and heart. The next [1]
  2. 2. What do they eat? How do they keep living? Horseshoe crabs eat worms, thin- Horseshoe crabs mate in late spring, shelled mollusks, crabs, and bits of early summer on sandy beaches. The fish. They have no jaw so they grind there food with the bristles on there females dig out holes in the sand legs and in their gizzard. The and lay 200 to 300 eggs in each. The gizzard contains sand and gravel. nests are below the high-water Place in the Food Chain mark. When the females are done Adult horseshoe crabs eat almost laying the eggs the males cover the anything. They eat clam, worms, eggs with sperm. The eggs will hatch scrape algae, and plants off of rocks. within several weeks. As said before they have no jaw so Responding to stimuli they grasp their food with their legs T h e r e h a s b e e n b e h a v i o r a l and use the spines on them to grind experiments on horseshoe crabs to it up. Other types of animals depend investigate there visual perception. on the horseshoe crab and their eggs H a b i t u a t i o n ( d e c r e a s e i n such as: shore birds, fish, and psychological response/behavioral turtles. re s p o n se t o s t i m u l i) t o l ig ht H o w d o t h e y b r e a t h ? occurred. Also males use brightness Horseshoe crabs have book gills and shape info. To recognize a mate. right directly behind there legs. They They are also able to regenerate lost let them breath underwater or on limbs. Also horseshoe crabs can use land as long as the gills remain wet. their tails to flip themselves over book gills get there name because when on their backs. they are alternating air pockets this causes them to look like a folded book. Top: Is a seagull eating a horseshoe crab. Middle: Shows the book gills.You can see how it resembles an open book. Bottom: Is a baby horseshoe crab. Right: Is an horseshoe crab on its back. [2]
  3. 3. T y p e o f s y m m e t r y Another group of extinct arthropods Th e h o r s e s h o e h a s b i l a t e r a l is the Trilobite. They are marine symmetry. Bilateral symmetry means arthropods that lived in the early if you would cut it in half it would be roughly the same on each side. Cambrian period. They went extinct E x t i n c t o r E n d a n g e r e d ? at the end of the Permian (250 million years ago). There are several types of horseshoe What’s the importance? crabs one that is considered e n d a n g e r e d i s t h e j a p a n e s e Horseshoe crabs are used in h o r s e s h o e c r a b ( Ta c h y p l e u s medical testing. Their blood has a Tridentatus). It is found in the Seto certain clotting reaction used in the Inland sea and is considered Limulus Amebocyte Lysate test to endangered because of loss of fi n d b a c t e r i a l e n d o t o x i n s i n habitat. Also there some extinct medicines. They are also used in species. Other extinct organisms in finding cures for diseases that can’t t h e M e r o s t o m a t a c l a s s a r e be cured by penicillin. Once the Eurypterids (sea scorpions). They are horseshoe crabs are used for there an extinct group of arthropods. They blood they are returned to the predate the earliest fishes. The ocean. In a week blood levels are largest type was Jaekelopterus witch able to return to normal. could measure up to 6 ft. 7 in. Top: Is a dipiction of a Eurypterid. Middle: Is a Japanese horseshoe crab Bottom: Is a picture of Limulus Amebocyte Lysate Left: Is a picture of a horseshoe crab [3]
  4. 4. Some Interesting Facts: 
 Horseshoe crabs have blue blood. They have ten eyes. Two of them are There blood contains hemocyanin witch has compound eyes located on the top of the copper in it. They don’t have hemoglobin. shell. The other eyes are scattered on Hemocyanin is technically colorless when the body. They are light sensors that not exposed to oxygen then when help navigate. exposed to oxygen it turns dark blue. Horseshoe crabs grow by molting. They grow twenty-five percent larger each time they molt. About after sixteen molts they are fully grown. [4]
  5. 5. Resources:‐crab‐Crabs‐Merostomata‐DIET.html http://www.beach‐ http://horseshoe‐‐crab‐eyes/ Pictures: Page 1: Flickr users: gregonbeeseʼs and Page 2: Flickr users: dirteernie,, and rainsgirl1889ʼs Page 3: Flickr users: , anna Ny, and la-blue-eyez, and koolpix also: Page 4:, moustermom, finiky, anna NY [5]