7 Trilobite Characteristics: 7 Facts You Should Know!

Trilobites are marine arthropods that are extinct; they mainly lived between the Cambrian period and the Permian period. Let us see a few characteristics features of trilobites.

  1. Trilobites have a pair of jointed antennae on the cephalon
  2. The mouth of trilobites have a ventral plate called the hypostome
  3. The body of trilobite is three-lobed and three-segmented; cephalon (head), thorax, and pygidium (tail).
  4. Trilobites have compound eyes
  5. Three or more pairs of legs are present in the thorax region of trilobites.
  6. The exoskeleton body of the trilobite is made out of chitin.
  7. Trilobites contain spines in the tail region that are used for swimming.
  8. The thorax region of the trilobite is highly segmented.

Let us discuss if trilobites are extinct, or if they are custaceans, isopods or amphibians along with some other facts in this article.

Are trilobites extinct?

Trilobites have a distinct head, thorax, and tail region that consists of about 10 orders and more than 20,000 species. Let us see whether the trilobites are extinct or not.

Trilobites are extinct marine arthropods that lived about 521 million years ago from the beginning of the Cambrian period to the end of the Paleozoic era for about 300 million years. Mainly the increase in the number of trilobite predators and volcanic eruptions lead to the mass eradication of the trilobite species.

The fiery eruption from the volcano sent trillions of tons of carbon dioxide into the atmosphere which lead to ocean acidification which in turn removed more than 95% of marine species during the end of the Paleozoic era. This was known as the “great dying”, which included the trilobites.

Are trilobites crustaceans?

Crustaceans come under the phylum arthropod which usually includes crabs, lobsters, barnacles, and branchiopods. Let us see whether trilobites are crustaceans or not.

Trilobites are not crustaceans, they are marine arthropods that are divided into head, thorax, and tail regions. They resemble crustaceans in many ways. They have appendages, exoskeletons, large compound eyes, and segmented antennae.

Are trilobites isopods?

Isopods are an order under the crustacean class, these animals are morphologically diverse that come in different shapes and sizes. Let us see if trilobites are isopods or not.

Trilobites are not isopods as trilobites are aquatic whereas the isopods live in different habitats like mountains, deep sea, and deserts. The body of trilobites has three lobes (Cephalon, thorax, and tail) but the isopods do not have lobes.

530px Ceratarges spinosus fossil trilobite Maroc
Image Credits: Ceratarges Spinosus Fossil Trilobite by James St. John (CC BY 2.0)

Are trilobites amphibians?

Amphibians are tetrapods, ectothermic vertebrates that live both on land and water. Let us see whether trilobites are amphibians.

Trilobites are not amphibians as they are marine invertebrates that are extinct now. 

Are trilobites carnivores?

An organism that mostly eats the flesh of other animals is called a carnivore. These are also known as predators. Let us see if trilobites are carnivores or not.

Trilobites are carnivores, they feed on small trilobites. They have diverse diets like insects and crustaceans. Some of them feed on algae and they have specialized structures to filter and feed on dung and detritus.

Are trilobites mammals?

Mammals are a group of vertebrates which nourish the young ones with milk that is produced by the mammary glands. Let us see if trilobites are mammals or not.

Trilobites are not mammals as they belong to the arthropod family that is classified as invertebrates. Trilobites also have exoskeleton whereas mammals only have endoskeleton.

Are trilobites vertebrates?

Vertebrates are animals that have a backbone and they are classified as a higher organism under the Animal kingdom. Let us see if trilobites are vertebrates or not.

Trilobites are not vertebrates as they lack backbone and they come under the phylum arthropod which is an invertebrate. The body has appendages and is divided into the head thorax and tail region. They have unique filter mechanisms that filter food from water currents and feed on them.


In this article, we have discussed some important characteristic features of trilobites with sufficient description.

Also Read: