Crustaceans Characteristics

Crustaceans belong to the subphylum of arthropods which is a very large group of aquatic creatures in the animal kingdom. This group includes creatures like lobsters, crabs, barnacles, shrimp, etc., which have very unique characteristics unlike any other animals in nature. The reasons behind these crustaceans characteristics are as unique as their features, since nature always has a plan for every living being. There are about 50,000 species which belong to these crustaceans in marine biology, and each have some or the other peculiarity to them. Their sizes range from about 0.1 mm to 12.5 ft, with various animals showcasing a number of characteristics across this group. These common characteristics of crustaceans are mentioned in the following paragraphs, so read on and find out interesting facts about them.

General Characteristics of Crustaceans

There is another group of arthropods, which are the insects, chelicerates and myriapods, that have very different characteristics than the crustaceans. However, they both belong to the same subphylum and therefore might have a few common characteristics. It is known that most of the crustaceans are marine animals, but some can either be terrestrial or parasitic in nature. Since we are discussing the crustaceans characteristics, they have a very unique set, irrespective of being aquatic or terrestrial. These major characteristics of crustaceans are with respect to their structures, digestive systems, reproduction and mobility. To give you a glimpse of these basic characteristics of crustaceans, we have put together most of them in the coming up paragraphs, take a look!

Head and Body
The most distinctive crustaceans characteristics are observed with respect to their body structures. They all have very well built heads, from which the five pairs of appendages are extended. The animal's antennae form the first two pairs of these appendages, through which the food, weather temperatures and dangers are detected. After the antennae, the next pair defines the mandibles or jaws, which are used for holding the food and tearing it. The next two pairs are the maxillae used for feeding. The other part of the body is segmented which comprises the thorax and the abdomen. Many crustaceans have additional abdomen features, i.e. legs used for swimming or "swimmerets". They also consist of the setae, thin whisker projections that extend from the head.

The Exoskeleton
Another very common yet unique one of the crustaceans characteristics is the exoskeleton found on their bodies. The exoskeleton covers the entire body of the animal including the head, appendages, thorax and the abdomen. It is a hard and calcified covering which is made up of limestone of commonly known as chitin. The reason nature has provided these crustaceans with the exoskeleton is because their internal systems are very delicate and are open immediately below the skeleton. They have an open circulatory system (no heart) and a two part nervous system (one ventral nerve and ganglia system). Thus, these delicate inner parts are protected by the exoskeleton.

Reproduction and Sexuality
Crustaceans follow sexual reproduction, wherein the males and females mate to produce offspring through eggs (oviparous). The eggs are usually carried by the female under her abdomen till they hatch where they undergo a series of metamorphoses. The two sexes are always distinguished by the swimmerets or pleopods, where the first pair of pleopods in males are meant for sperm transfer. A few crustaceans are also known to be hermaphrodites, where the organism consists of both the male and female reproductive organs, e.g.: barnacles.

Feeding and Diet
Crustaceans are hunters like any other animal, and hence they have to hunt for their prey with the help of their appendages. They hunt for small fish when they are in water, or other aquatic animals. However, the smaller crustaceans are known to be scavengers who feed on dead material. These animals use their setae for creating currents in the water, so that their prey doesn't escape and ends up into their mouth! Their diet can be smaller animals and sometimes plankton.

With these common crustaceans characteristics, I am sure now, you know how to distinguish these animals from the others. They are very interesting creatures found in nature and studying them can be a real pleasure!