Anthropods Facts & Worksheets

Invertebrates having jointed legs are known as arthropods. They account for around 75% of all creatures on Earth and act as pollinators, nutrient recyclers, scavengers, and food for other animals that play essential roles in ecosystem management. Many of the animals we see in our gardens, such as spiders, ants, and centipedes, are among them.

See the fact file below for more information on Arthropods, or you can download our 30-page Arthropods worksheet pack to utilize within the classroom or home environment.

Key Facts & Information

ARTHROPODS

• “Arthropod” is derived from the Greek words ἄρθρον árthron, “joint,” and πούς pous (gen. podos (ποδός)), “foot” or “leg,” which together mean “jointed leg.”
• Arthropods are invertebrates having an exoskeleton, segmented bodies, and paired jointed legs that are members of the phylum Arthropoda.
• More than one million known invertebrate species of arthropods are classified into four subphyla: Uniramia (five classes, including insects), Chelicerata (three classes, including arachnids and horseshoe crabs), Crustacea (crustaceans), and Trilobita (trilobites).
• All arthropods are bilaterally symmetrical, with a segmented body covered by an exoskeleton made of chitin that serves as armor and a surface for muscle attachment. Each body segment can have two joint appendages. 
• Appendages help with eating, feeling, sensing, mating, respiration, movement, and defense.
• Arthropods are often regarded as the most successful creatures on the planet. The phylum has more species and individuals than all other animal groupings combined.
• The phylum includes carnivores, herbivores, omnivores, detritus feeders, filter feeders, and parasites in practically any ecosystem, both aquatic and terrestrial.

SCIENTIFIC CLASSIFICATION

• Arthropods are any member of the phylum Arthropoda, the largest animal kingdom, which includes familiar forms such as lobsters, crabs, spiders, mites, insects, centipedes, and millipedes. 
• This phylum contains approximately 84 percent of all known animal species. 
• Arthropods can be found in every habitat on Earth and have a diverse set of adaptations.

CHARACTERISTICS

• An Arthropod possesses all of the following.
  • The body is segmented, triploblastic, and bilaterally symmetrical.
  • They are organized at the organ system level.
  • The body is separated into three parts: head, thorax, and belly.
  • Their bodies have jointed appendages that aid in locomotion.
• The coelomic cavity is blood-filled.
• They have a free-flowing circulatory system.
• On the head, there are two compound eyes.
• Chitin is used to make the exoskeleton.
• Terrestrial Arthropods excrete via Malpighian tubules, whereas aquatic Arthropods excrete via green glands or coxal glands.
• They are unisexual, with either external or internal fertilization.
• They have an advanced digestive system.
• They breathe through the general body surface, also known as the trachea.
• Sensory organs such as hairs, antennae, simple and compound eyes, auditory organs, and statocysts are found in them.
• Arthropods are a motley crew that includes cockroaches, crabs, butterflies, beetles, centipedes, scorpions, shrimp, spiders, lobsters, lice, ticks, termites, potato bugs, and sea monkeys (also known as brine shrimp). These evolutionary relatives may trace their ancestors back 600 million years to a common ancestor that lived in the primordial waters before vertebrates or land plants arose.
• On the surface, the arthropods appear unrelated, yet the familial resemblance is more apparent when compared to other main groupings of creatures (like mammals, mollusks, or bacteria). A variety of traits separate arthropods from other species, including:
  • A body with segments. A centipede’s body, for example, vividly demonstrates the segmentation shared by all arthropods.
  • Segmented legs (arthro = jointed, pod = foot). An arthropod leg often contains numerous joints.
  • Bilateral Symmetry (i.e., the left and right sides of the organism are mirror images of each other).
  • An exoskeleton (i.e., a rigid covering encapsulating each body segment).
  • Molting (i.e., the shedding of the exoskeleton, which enables growth). For example, a cicada emerges from its old exoskeleton.

CLASSIFICATIONS

• Extant forms of the phylum Arthropoda are typically split into four subphyla: Chelicerata (arachnids), Crustacea (crustaceans), Hexapoda (insects and springtails), and Myriapoda (millipedes and centipedes).
  • Chelicerata: Chelicerata (from the Greek word chela, which means claw) is an arthropod subphylum that contains spiders, mites, scorpions, and horseshoe crabs. 
  • Chelicerates, unlike other arthropods, lack antennae. They also lack the mandible food-processing appendages other arthropods utilize to break and ground food. Instead, they have chelicerae, clawed appendages to grip and shred food. 
  • The majority of chelicerates are terrestrial, except marine spiders and horseshoe crabs.
• Myriapoda: Land-dwelling arthropods such as centipedes and millipedes are known as members of the subphylum Myriapoda. There are roughly 13,000 species in this category, with no marine myriapod species known.
• They feature a single set of antennae and mouthparts similar to chelicerates. Myriapods are distinguished by the many jointed legs that protrude from their elongated worm-like bodies. 
• The name of the subphylum is derived from Greek root words that imply “countless feet.” Myriapods have anything from 10 to 750 legs.
• Insects are the most diversified members of the Hexapoda subphylum. Hexapods have a particular body design that consists of three major sections:
  • A head
  • A thorax
  • An abdomen with three pairs of thoracic legs
  • And one pair of antennae.
• Hexapods: Hexapods have three jaws: mandibles, maxillae, and labium. Insects breathe by sucking air into their trachea tubes through spiracles. Unlike in arachnids, these tubes do not terminate at the lungs but instead branch into smaller networks of lines known as tracheoles, which radiate straight into the insect’s tissues for gas exchange.
• Although there is no active air pumping, every slight movement in the insect body causes airflow throughout the trachea.
• The Crustacea subphylum contains the majority of marine arthropods.
• Crustaceans: Most crustaceans live in the water, where they are so numerous that they are often referred to as “insects of the sea.” Crabs, shrimp, and lobsters are widespread along the seashore. Some shrimp, known as krill, spend their lives as plankton, floating on the open ocean’s surface waters. 
• Some crustaceans, such as crayfish, dwell in freshwater lakes and streams; others, such as isopods and pill bugs, live on land. 
• Both giant animals and humans eat many crustaceans. The barnacle is an exception to the rule that most crustaceans are mobile. Barnacle larvae swim freely, but as they mature, the head shrinks and is glued to the substrate with a powerful chemical adhesive.
• The phylum Arthropoda also comprises the extinct subphylum Trilobitomorpha. This group includes trilobites, the dominant arthropods in the early Paleozoic oceans (541.0 million to 251.9 million years ago). 
• Trilobites became extinct during the Permian Period near the end of the Paleozoic Era (298.9 million to 251.9 million years ago). 

EVOLUTION

• Arthropods have existed for a very long period. Their forefathers appeared 530 million years ago in the Cambrian oceans, at a time that is only partially understood. 
• Arthropod fossils have been discovered dating back to the Cambrian epoch (over 500 million years ago). The trilobites, an ancient subphylum of marine arthropods, are the most widespread collection of arthropod fossils.
• Arthropods are the protostomes’ evolutionary climax. Arthropods appear to have developed from the same root as annelids, with the three major lineages of arthropods – the Chelicerata, Crustacea, and Insecta – evolving separately from a common ancestor.
• Arthropods persist today because of their ability to adapt to changing settings over such a long period.

REPRODUCTION AND DEVELOPMENT

• Arthropods must molt (shed) their exoskeletons regularly to grow. They generate an enormous exoskeleton during the molt to allow for growth. A suit of armor is equivalent to the combination of an exoskeleton with jointed limbs.
• Vertebrates, on the other hand, such as fish and humans, have an internal skeleton, known as an endoskeleton, with muscles linked to its outer surface.
• Arthropods are often dioecious (have two distinct sexes), and in many species, development is indirect, which means that the juvenile form is a larva that looks substantially different from the parent and goes through a process called metamorphosis to convert to the adult body plan. The transition of lepidopteran insects from caterpillar to butterfly is a striking illustration of this life cycle.
• Arthropods mainly reproduce sexually. Some arthropods, such as barnacles, are hermaphroditic, meaning they have organs from both sexes. In comparison, few crustaceans and insects can reproduce by parthenogenesis. When circumstances improve, they resume sexual reproduction.

Arthropods Worksheets

This fantastic bundle includes everything you need to know about Arthropods across 30 in-depth pages. These ready-to-use worksheets are perfect for teaching kids about Arthropods, a diverse group of animals that includes insects, crustaceans, arachnids, and myriapods.

Complete List of Included Worksheets

Below is a list of all the worksheets included in this document.

• Arthropods Facts
• Spot the Impostor
• Trait Blocks
• Molting Process
• The Four Groups
• Crossword
• Case Solving
• Taxonomy Feud
• Word Cloud
• Arthropoda
• My Arthro Pokemon

Frequently Asked Questions

What are arthropods?

Arthropods are a phylum of invertebrate animals that includes insects, crustaceans, arachnids, and myriapods. They are characterized by having an exoskeleton, a segmented body, and jointed appendages.

What are the characteristics of arthropods?

Arthropods have a hard exoskeleton that provides protection and support for their bodies. They also have segmented bodies and jointed appendages, which allow for greater mobility. Their nervous system is composed of a brain and a ventral nerve cord. They have a wide range of sizes, from tiny insects to large crustaceans such as lobsters and crabs.

What are the different types of arthropods?

There are four main classes of arthropods: Insects, Arachnids, Crustaceans, and Myriapods. Insects include ants, beetles, butterflies, and moths. Arachnids include spiders, scorpions, and ticks. Crustaceans include lobsters, crabs, and shrimps. Myriapods include centipedes and millipedes.

What is the ecological importance of arthropods?

Arthropods are an important group of animals in many ecosystems. They play a vital role in pollination, decomposition, and food webs as both predators and prey. They also serve as indicators of environmental health, as changes in arthropod populations can indicate changes in the health of an ecosystem.

How do arthropods adapt to different environments?

Arthropods are able to adapt to a wide range of environments by developing specific physical and behavioral adaptations. For example, some insects have adapted to living in extremely dry environments by developing the ability to retain water in their bodies. Other arthropods, such as certain crustaceans, have adapted to living in deep sea environments by developing the ability to survive in extreme pressure and cold temperatures.

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