Horseshoe crabs are not crabs, they are in the arthropod family and related to spiders and scorpions.
They have been on the planet for 445 million years and they’ve changed very little during that time.
The oldest land animals date to about 415 million years ago. Those early land residents were scorpions, spiders and insects; the horseshoe crab’s closest living relatives.
Horseshoe crab eggs. Image by:Piotr Naskrecki
The female can lay up to 80,000 eggs a season.
Shorebirds eat many of the eggs before they have a chance to hatch.
Their eggs are a main source of food for millions of migratory birds.
Image Rob J:citybirder.blogspot.com
After 4 to 30 days the larvae emerge.
A Red Knot might eat 24,000 horseshoe crab eggs a day.
Horseshoe crabs spend the first two years of their life close by to where they hatched. Then they will travel to deeper water.
They molt about 6 times during their first year.
They can not reproduce until they are 9 to 11 years old.
They can live up to 30 years.
Medical Use:
They have baby blue blood.
They have copper in their blood (hemocyanin), not iron (hemoglobin).
Their blood protects them from infection. For this reason, their blood is capable of detecting toxins in medical applications.
在马蹄蟹血细胞中发现的一种化学物质,可以检测出任何溶液中的病毒、细菌毒素或污染物,然后将污染物困在凝块中。鲎试剂(LAL)用于测试所有处方药物、疫苗、静脉注射液、外科植入物和其他进入皮肤下的医疗设备的纯度。LAL可以检测到低至万亿分之一的污染物。
采集马蹄蟹的血液需要在野外采集它们,把它们绑在架子上,用针扎进它们的心脏,然后抽出它们三分之一的血液。然后把它们放回大海。70%到85%的人能熬过这场考验。
马蹄蟹血可以卖到1.5万美元一夸脱。在美国,只有五家公司获得了FDA的生产和销售LAL的许可。
A protein from horseshoe crab blood is under going tests as an antibiotic.
2012年,美国有61万多只马蹄蟹被用于生物医学目的。马蹄蟹的圈养寿命不超过两年,所以它们是在野外捕获的。
Females are 20-30 percent larger than males.
Their brain’s are doughnut-shaped and encircle the mouth.
They can regrow lost limbs.
Their shells are composed of chitin.
Having shells of chitin (think beetle or lobster shells) rather than of calcium carbonate (shells, eggshells) makes them able to tolerate low-oxygen water and ocean acidification.
胡里奥·里波尔的马蹄蟹眼。Julio Ripoll建筑公司迈阿密。
Horseshoe crabs have 9 eyes and can see UV light. They are the oldest living animal with compound eyes.
© Jürgen Freund,www.jurgenfreund.com
They can swim upside down.
Environment:
它们只分布在北美东海岸和亚洲东海岸(但泰国和缅甸的西海岸也有)。
它们生活在浅水和大陆架的泥土和沙子中,但不生活在水深超过100英尺的地方。
Horseshoe crabs have survived over 12 major extinction events.
They love muddy water and eat worms and mollusks on the seafloor.
Seagulls will eat them if overturned on a beach. Loggerhead sea turtles eat adolescent and adult horseshoe crabs.
The largest population in the world show up in Delaware Bay during mating season.
马蹄蟹交配。Image by:Piotr Naskrecki
Mating:
交配季节一年只有一次,在5月或6月的满月和/或新月高潮的时候。
During the breeding season, horseshoe crabs head toward shallow coastal waters.
They do not venture toward shore when the surf is rough.
The male fertilizes the eggs after the female releases them in the sand close to the high tide water line. The male holds onto the back of the females shell while she lays the eggs. If there are less females than males, extra males will stay near a mating couple to help fertilize the eggs.
The female releases her eggs in clusters of about 4000. She will release about 4 or 5 clusters per high tide. Therefore she must come up to the high tide waterline for 4 or 5 high tides.
A male might hold onto a female for days during mating season.
In Decline
Many millions of horseshoe crabs have been used by humans as fishing bait and for fertilizer. In Asia the are also eaten by humans.
When their numbers started to drop precipitously, the Atlantic States Marine Fisheries Commission set restrictions.
这三种亚洲物种都在严重减少。
千万不要抓住马蹄蟹的尾巴。
Each spring during breeding season about 10% of the horseshoe crab population dies when rough surf flips them onto their backs. The ‘Just Flip ’em’ campaign asks that you gently turn them onto their stomachs. Have no fear, they are gentle creatures. They do not bite. But we do.
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Resources:
PBS: Crash: A Tale of Two Species:pbs.org
huffingtonpost.com/2014/03/12/horseshoe-crab-blood
theatlantic.com/2014/02/the-blood-harvest/
New Jersey, South Carolina and Fire Island, NY. have moratoriums on harvesting. In Delaware harvesting is restricted to males only. – See more at: https://web.archive.org/web/20150915003723/https://www.inspirationgreen.com/horseshoe-crab-facts.html#sthash.NInZffKV.dpuf
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