Many believe that mantis shrimp have not evolved at all, although with closer consideration multiple changes are evident.
One of the most noticeable traits is the raptorial appendages (red arrow). The raptorial appendages in the modern mantis shrimp are much larger and highly specialized for predation.
In recent years it seems the mantis shrimp has had no need to adapt as they seem to be fully prepared for everything in their natural environment. With the best, most complex eyes containing 16 colour-receptive cones (humans only contain 3) they can see ultraviolet lights to help avoid predators and track down prey. As well as an appendage that strikes with a spring-like motion, with the ability to strike 50 times faster than the blink of an eye (the same speed as a .22 caliber bullet), the mantis shrimp seems to be prepared for anything.
Now on the other hand, humans are creating multiple issues including the destruction of many coral reefs in which the the mantis shrimp inhabit. Humans are constantly polluting the water through oil spills, fertilizer runoff, and human waste that is dumped into the ocean. Along with the carelessness of boaters and fisherman, the uneducated scuba diving of tourists and the increasing amount of cyanide injections in order to stun fish to collect for domesticated aquariums, it seems coral reefs are dying off by the day. In the future mantis shrimp will have to adapt to live with more toxic water levels. As well as be able to survive in open ocean floors where there is less places to find cover from predators. Possibly meaning the mantis shrimp will have to evolve with less bright, variant colours in order to blend in with its new surrounding.
The mantis shrimp generally reproduce all year round, but have peak mating season during the warmer months of the year. Mantis shrimp have two sexes, male and female. I was unable to find the genetics of the sexes of mantis shrimp. Male mantis shrimp tend to be much more colourful than the female mantis shrimp, the males vibrant colours attract females in order to mate. This is beneficial because female mantis shrimp often chose the strongest, most colourful male. Meaning that the males that carry the best genetics pass them onto the next generation. The fertilization is external. The male releases sperm out of its external copulatory organ, which is then collected by the female. Once the sperm is collected, the female uses it to fertilize her eggs that she is holding inside. After the eggs are fertilized, the female brings them to a burrow for safe development. Mantis shrimp have a gestation period of 9 - 60 days, the average is 40 days. Mantis shrimp babies are hatched from an egg.
The mantis shrimp uses DNA for its chromosomal material. I was unable to find the the number of chromosomes the mantis shrimp has, but they are very closely related to the common shrimp which has 254 chromosomes. I was unable to find how the chromosomes in the mantis shrimp are arranged. There are no known genetic conditions that affect mantis shrimp. Although some genetic conditions can be found in the common shrimp. Such as cramped shrimp which is a condition in which the tail is drawn under the shrimp's body and becomes so rigid to the point it is unable to be moved.
*These are created alleles and may not be scientifically accurate
Mantis shrimp with blue tail have the dominant trait for colouration (T). Mantis shrimp with red tail have the recessive trait for colouration (t).
Mantis shrimp with with arched antennules have the dominant allele for shape (A). Mantis shrimp with straight antennules have the recessive trait for shape (a).
A male mantis shrimp homozygous for blue tail and heterozygous for arched antennules mates with a female mantis shrimp heterozygous for blue tail and homozygous for straight antennules.
The female is (Ttaa) with the possibility of Ta or ta
The male is (TTAa) with the possibility of TA or Ta
This shows that 100% of of the offspring will have a blue tail. Also, 50% of the offspring will have arched antennules and 50% will have straight antennules. The genotypes of the offspring can be described as a 1:1:1:1 ratio.
- 1: homozygous blue tail, heterozygous arched antennules
- 1: homozygous blue tail, homozygous straight antennules
- 1: heterozygous blue tail, heterozygous arched antennules
- 1: heterozygous blue tail, homozygous straight antennules
Mantis shrimp have a complex digestive system.
The cardiac stomach plays a very important role in the mantis shrimp's digestive system. The folded and muscular stomach is lined with rows of stiff bristles, teeth and filtering setae known as gastric mill. The cardiac stomach is large enough to hold remains of prey. It opens directly from the mouth without intervening with the esophagus. The mantis shrimp ingests food through its mouth, the food is then sent to the cardiac stomach where it is mashed and grinded. After that, the mashed up food goes to the pyloric stomach where it is absorbed by digestive glands which contain many enzymes that break down food and absorb nutrients. Then, the remainder of the food is sent through the intestine where more nutrients is absorbed. Finally, the waste is sent to the anus and disposed of.
The main food source for the mantis shrimp is clams, crabs and snails although certain mantis shrimp eat small fish because they primarily use a spearing technique to kill prey. These food sources provide essential proteins and omega-3 acids to help the mantis shrimp grow stronger as their strength is the main attribute used for defense.