Perhaps one of the last commercially important species that is still harvested from 圣. 约翰河是蓝蟹. According to 圣 Johns River Report, over 1.2 million pounds valued at $3.1 million of both hard- and soft- shell crabs were 摄于2022年. Duval County accounted for just over 500,000 pounds worth $1.300万年. The extent of the crabbing effort is seen by anyone boating on the river. 有 countless crab traps tethered to originally multi-colored floats which over time, become dark with growth and often difficult to see.
Blue crabs happen to be one of my favorite animals. Partly because I grew up crabbing with fish heads and a dip net on the Chesapeake Bay in Virginia, and along the Outer 北卡罗来纳银行. Partly because I love to eat crab meat in any form: crabcakes, she-crab soup, or just picking steamed crabs with Old Bay as my go-to seasoning. 但 mostly because the neurophysiology of the swimming leg musculature was the topic of 我的硕士论文研究. One benefit of doing research on blue crabs, any specimens not subject to dissection and experimentation could be eaten.
The scientific name of the blue crab is Callinectes sapidus. Callinectes是美丽的意思 swimmer, while sapidus means tasty or savory. They truly are tasty, beautiful swimmers. Crabs are Decapods and have 10 legs. The first pair of legs are modified into claws with one sharp and pincher-like, while the other is stronger and more crusher-like. The middle three sets of legs are walking legs that can propel the critter across 底部. The beauty is in the last pair of legs which are paddle-like and allow 螃蟹要游泳. The leading leg sort of sculls to lift the animal up while the rear leg sweeps back and forth to push the crabs forward.
The life cycle of the blue crabs is amazingly complex. They are crustaceans that have a hard shell of a body, so in order to grow, they must molt, or shed their old shell, enlarge themselves and allow their new shell to harden. Females, whose underside apron or abdomen looks like the US Capitol’s rotunda, give off a chemical scent as they 准备蜕皮. Males, whose abdomen looks like the Washington Monument, can sense the expectant female molt and will pick up the pre-molting female and carry her around 直到她蜕皮.
Immature female crabs have a triangular apron on their abdomen. 雌性只蜕皮 一次交配前. After mating, female crabs move into higher salinity waters in order to release their larval crabs.
After about two months, the she-crab apron becomes distended with a large, yellow/orange sponge mass containing 1 to 300万年 eggs. Only a few of those eggs will become an adult with a life expectancy of 2 to 4 years. Female crabs carry the eggs for about two weeks before hatching or releasing the zoea. The orange mass becomes darker as 幼虫发育. Eggs hatch into microscopic zoea larvae and are flushed out of the river into the Atlantic where they float freely as zooplankton. 海蟹幼虫变换 into megalopa after about 40 days and a dozen or so molts depending on water temperature 还有食物供应.
The zoea and megalopa are transported back into the estuary in an very elegant manner
with up-and-down swimming in the water column. They swim up on the incoming tide and
down to 底部 on the outgoing tide. So they sort of seesaw back into the river
where over the next 12 to 18 months they grow and mature. 只是为了开始这个循环
再来一遍.
很高兴你问了河流生活
Can you recommend a few good books that might be fun reads for the summer?
If you want to learn more about 圣. Johns River, then read River of Lakes: A Journey 在佛罗里达大街上. Johns River by Bill Belleville. Then there is a must read for anyone living in Florida in the historical fiction novel A Land Remembered by Patrick Smith. While fiction, there is a lot of historical truth in the story. 也是我的最爱 mine about crabs is Beautiful Swimmers: Watermen, Crabs and the Chesapeake Bay by 威廉·华纳. It is a well written and illustrated book about blue crabs in the Chesapeake Bay that also applies to northeast Florida.
