Content
- Starfish of the order Brisingida
- Starfish of the order Forcipultida
- Starfish of the order Paxilosida
- Starfish of the order Notomyotida
- Starfish of the order Spinulosida
- Starfish of the order Valvatida
- Starfish of the Velatida order
- Other examples of types of starfish
Echinoderms are a phylum of animals that have an important diversity of exclusively marine fauna. In PeritoAnimal, we want to introduce you in this article to a specific group of this phylum, which is represented by the class Asteroidea, which we commonly know as starfish. This class consists of about a thousand species distributed in all the oceans of the world. Eventually, another class of echinoderms called Ophiuras are designated as starfish, however, this designation is not correct, since, although they present a similar aspect, they are taxonomically different.
Starfish are not the most primitive group of echinoderms, but they have all their general characteristics. They can inhabit the beaches, be on rocks or on sandy bottoms. We invite you to read on to learn more about types of starfish that exists.
Starfish of the order Brisingida
The order of the brisingidos corresponds to starfish that inhabit exclusively the bottom of the seas, generally between 1800 and 2400 meters deep, being distributed especially in the Pacific Ocean, in the waters of the Caribbean and New Zealand, although also some species are found in other regions. They may have from 6 to 20 large arms, which they use to feed by filtration and which have long needle-shaped spines. On the other hand, they have a flexible disk on which the mouth is located. It is common to observe species of this order on marine cliffs or areas where there are constant currents of water, as this facilitates feeding.
The Brisingida order is formed by two families Brisingidae and Freyellidae, with a total of 16 genera and more than 100 species. Some of them are:
- Brisinga decacnemos
- american novodine
- freyella elegans
- hymenodiscus coronata
- Colpaster edwardsi
If you want to know more details about the life of starfish, also visit our article on reproduction of starfish, where you will see an explanation of how it works and examples.
Starfish of the order Forcipultida
The main characteristic of this order is the presence of pincer-shaped structures on the animal's body, which can open and close, called pedicelareas, which are generally visible in this group and are formed by a short stalk that contains three skeletal pieces. In turn, the ambulatory feet, which are the soft extensions arranged on the lower part of the body, have flat-tipped suction cups. The arms are usually quite robust and have 5 or more spokes. They are widely distributed on a global scale, both in tropical and cold waters.
There is divergence as to its classification, however, one of the accepted ones considers the existence of 7 families, more than 60 genera and about 300 species. Within this order, we find the common starfish (Asterias rubens), one of the most representative, but we can also find the following species:
- Coscinasteria tenuispina
- labidiaster annulatus
- Ampheraster alaminos
- Allostichaster capensis
- Bythiolophus acanthinus
Starfish of the order Paxilosida
Individuals in this group have tube-shaped ambulatory feet, with rudimentary suction cups, when present, and are characterized by having small granule structures on the plates covering the upper skeletal surface of the body. It has 5 or more arms, which help to dig the sandy soils where they can be found. Depending on the species, they may be in different depths and even inhabiting very superficial levels.
This order is divided into 8 families, 46 genera and more than 250 species. Some are:
- Astropecten acanthifer
- Ctenodiscus australis
- ludia bellonae
- Gephyraster Fisher
- Abyssaster planus
Starfish of the order Notomyotida
You ambulatory feet of this type of starfish are formed by series of four and have suckers at their extremes, although some species do not have them. The body has considerably thin and sharp spines, with arms formed by very flexible muscle bands. The disc is relatively small, with the presence of five rays and the pedicel can have different shapes, such as valves or spines. The species of this group live in deep waters.
The order Notomyotida is formed by a single family, the Benthopectinidae, has 12 genera and about 75 species, among which we can mention:
- Acontiaster bandanus
- Benthopecten acanthonotus
- smelt echinulatus
- Myonotus intermedius
- Pectinaster Agassizi
Starfish of the order Spinulosida
Members of this group have relatively delicate bodies and as a distinctive feature they do not have pedicelarias. The aboral region (opposite the mouth) is covered with numerous thorns, which vary from one species to another, both in size and shape, as well as in arrangement. The disc of these animals is usually small, with the presence of five cylindrical rays and the ambulatory feet have suction cups. The habitat varies and may be present in intertidal or deep water zones, both in polar, temperate and tropical regions.
The classification of the group is controversial, however, the world record of marine species recognizes a single family, the Echinasteridae, with 8 genera and more than 100 species, such as:
- bloody Henricia
- Echinaster colemani
- Subulata metrodira
- Violet Odontohenricia
- Rhopiella hirsuta
Starfish of the order Valvatida
Almost all species of starfish in this group have five tubular shaped arms, in which there are two rows of ambulatory feet and striking ossicles, which are limestone structures embedded in the dermis that bring rigidity and protection to the animal. They also have pedicels and paxillas on the body. The latter are umbrella-shaped structures that have a protective function, with the aim of preventing the areas through which they eat and breathe from becoming obstructed with sand. This order is quite diverse and individuals ranging from a few millimeters to over 75 cm can be found.
The Valvatida order is highly controversial with regard to its taxonomy. One of the classifications recognizes 14 families and more than 600 species. Some examples are:
- pentaster obtusatus
- nodosus protoraster
- devil clarki
- Alternatus heterozonia
- linckia guildingi
Starfish of the Velatida order
The animals of this order have usually robust bodies, with large disks. Depending on the species, they have between 5 and 15 arms and many of these have an underdeveloped skeleton. There are small starfish, with diameters between 0.5 and 2 cm, and others up to 30 cm. As for size, the class varies between 5 and 15 cm from one arm to the other. Ambulatory feet are presented in even series and usually have a well-developed suction cup. As for pedicelaria, they are usually absent, but if they do have them, they consist of groups of thorns. The species of this order live in great depths.
5 families, 25 genera and around 200 species, among those found:
- belyaevostella hispida
- Caymanostella Phorcynis
- Korethraster hispidus
- Asthenactis australis
- Euretaster attenuatus
Other examples of types of starfish
Beyond the types of starfish described throughout this article, many more stand out, such as the following:
- gibbous asterina
- Echinaster sepositus
- Marthasterias glacialis - thorn starfish
- Astropecten irregularis
- Luidia ciliaris
Starfish have an important ecological role within marine ecosystems, so they are of great relevance within them. However, they are highly susceptible to chemical agents, as they cannot easily filter out toxins that increasingly enter the oceans.
There are several species that are commonly found in coastal areas that have tourist use and it is common to observe how visitors to the place take the starfish to observe them and take pictures, which is quite an attitude. harmful to the animal, as it requires being submerged to be able to breathe, so, shortly after they are out of the water, they die. In this regard, we must never take these animals out of their habitat, we can admire them, always keeping them in the water and not manipulating them.
If you want to read more articles similar to Types of Starfish, we recommend that you enter our Curiosities section of the animal world.