Starfish are invertebrates belonging to the edge of echinoderms. The bodies are formed by five or more long arms attached to a central disk, giving them the star’s appearance.
Up to 1600 different species have been identified in this same class of animals. Nowadays, you can see them in the following animated pictures below.
Starfish Animated Images
It is one of the most common and known seafloor inhabitants, usually in various sizes and colors. Many starfish species are at risk of extinction due to their habitat’s destruction due to human activities in the oceans.
The starfish body contains a variety of curiosities; for example, it has no brain or blood. In general, starfish species have five arms, but some can have up to 50 of them, like the Labidiaster annulatus or Antarctic starfish.
These arms are born from the central disc of the body and can be short or long. Under the central disc is the mouth of the star.
Another curious fact is the regeneration capacity of its members or its entire body. That is, the same star generates another arm if it loses one.
Starfish have a calcified skin that protects them from most predators and is often red, orange, blue, gray, or brown: these bright colors have the function of scaring or camouflaging.
The surface can be of a great variety of textures: smooth, coarse, spiny, etc. but always covered by overlapping bone plates.
The internal skeleton is formed by calcareous ossicles or plates that can articulate between each other. The starfish have a water vascular system that opens in the madreporite, an opening located in the body’s central part.
This madreporite leads to a composite stone channel. In turn, the stone channel is connected to a track that leads to each of the star’s radial channels.
Locomotion (movement) is given, from the water vascular system, by the tube feet, which have sensory functions and are positioned at the end of each radial channel.
Most species measure from 12 to 24 centimeters in diameter, but some measure less than 2 centimeters, and others are more than 1 meter in diameter.
Starfish inhabit all of the earth’s oceans and can be found in cold, tropical waters. It is possible to encounter some specimen of this echinoderm both on the surface and more than 6,000 meters below the sea’s surface.
Although it may not seem so, starfish are carnivorous animals. Every day they consume prey that is easy to hunt, such as barnacles, bivalves, and many other invertebrates.
The stomach of the starfish is what we would call “evaginable”, meaning that they can “expel” it from the body.
The star begins by taking the prey with its arms, then proceeds to expel the stomach, and thus the prey is impregnated with digestive juices, and finally “fold” the stomach and digest the prey.
Although in most asteroids, the female and male can reproduce sexually, the truth is that there is no single type of reproduction of the starfish.
Some starfish are hermaphrodites, and both the female and the male can produce eggs and sperm simultaneously, which occurs thanks to an organ or a gonad that scientists know as ovotestis.
There is sequential hermaphroditism in other species, which means that some individuals are born of one sex and then change to the opposite sex.
In the case of certain species of the asteroid class, males become female as they age. In this class, we observe quite peculiar processes related to reproduction and sexuality.
For example, the starfish species whose females can be divided, and the resulting half is always male.