Arthropoda
Characteristics of Arthropoda:
- They have segmented bodies that are arranged into regions, called tagmata (e.g., head, thorax, abdomen).
- paired appendages (e.g., legs, antennae) are jointed.
- They posses a chitinous exoskeletion that must be shed during growth.
- bilateral symmetry.
- The nervous system is dorsal (belly) and the circulatory system is open and ventral (back).
Shrimp
Shrimps mature first as males before changing into females. They are called protandric hermaphrodites because they do that. At 2 ½ years of age, shrimp mature as males and fertilize older females in offshore waters. After breeding the males change into females. Adult females move into inshore waters to spawn. Male shrimp will seek out a female that is ready to molt and guard her as his own until she is ready to mate, protecting her from other males. When she is, the pair will lock together and copulate for several seconds and then swim together for hours or even days. In others, the male is seemingly unable (or finds it unnecessary) to recognize a pre-molt female. Instead, he interacts with as many females as needed until he finds one that is ready to mate. In these cases, the male and female separate quickly after copulation. During copulation, the female produces a gelatinous mass and holds it between her fourth pair of walking legs for the male to deposit sperm into it. Next, the female lays as many as 15,000 eggs in the gelatin for the sperm to fertilize. In most species, the female will care for the fertilized eggs in what is called a brood chamber that is located on the underside of her tail. However, some species will scatter their eggs in the water to develop on their own.
Crabs
In the process of mating, the female and male crabs assume the "doubler position." In this position, the male carries the female while they copulate. Copulation lasts about 5 hours but the crabs may stay together in the double position for days. The female stores the male's sperm on the underside of her abdomen. The stored sperm will be used by the female two more times in future spawning events.
The female crab migrates to saltier waters after mating and then attaches 100,000 to 2,000,000,000 eggs to the stored sperm on her abdomen. The eggs incubate for about 2 weeks until they hatch and crawl/swim away from their mother. The crab larvae grows for around 40 days until they reach maturity.
Mantises
Contrary to the popular, belief, the male mantis is not always consumed by the female after the reproduction process. Although true in captivity, this cannibalism of the male mantis rarely happens in the wild. Most female mantises are flightless and attract males (much smaller than the female) by emitting a species-specific chemical (pheromone). Before sex, The male performs a courtship routine before climbing on to the female's back to mate. Mantis reproductive organs are located on the tip of the abdomen. The male fertilizes the female and flies away to mate with other females.
Female mantises lay between 10-400 eggs using the ovipositer on the tip of the abdomen. These eggs are cased in an ootheca (egg case) made from a frothy substance produced from the female's abdomen. The ootheca is comprised of many "rooms" in which a single egg is held in. These rooms also consist of a one-way door allowing the mantises to hatch and climb out. The ootheca hardens after being baked by the sun and offers the eggs protection from predators and other environmental hazards.
Female mantises lay between 10-400 eggs using the ovipositer on the tip of the abdomen. These eggs are cased in an ootheca (egg case) made from a frothy substance produced from the female's abdomen. The ootheca is comprised of many "rooms" in which a single egg is held in. These rooms also consist of a one-way door allowing the mantises to hatch and climb out. The ootheca hardens after being baked by the sun and offers the eggs protection from predators and other environmental hazards.