Introducing KNOVA — A free reading app with curriculum-aligned passages on History & Science for Grades 3-8Learn More →

Are Snails Insects? — Reading Comprehension

No ratings yet

Premium Resource

Grades

Rate this resource

Send Feedback / Report an Issue

About This Reader

This comprehensive science passage, designed for middle school students, clarifies the common misconception that snails are insects. It provides a detailed explanation of biological classification, or taxonomy, to distinguish between the two. The passage describes the defining characteristics of snails as mollusks (phylum Mollusca) and compares them to the defining traits of insects as arthropods (phylum Arthropoda). Key concepts such as the snail's soft, unsegmented body and shell, and the insect's segmented body and exoskeleton, are explained with clear and direct language. The text is aligned with NGSS standards related to organisms' structures and functions, making it a valuable resource for teachers and students.

CONTENT PREVIEW

Snails and insects are often found in similar environments, such as gardens and forests, which can lead to confusion about their classification. However, they belong to entirely different scientific categories. All living things are organized into a hierarchical system of classification, starting with broad categories and narrowing down to specific species. This system, known as taxonomy, helps scientists understand the relationships between different organisms. At the highest level, snails and insects are both in the Kingdom Animalia, but their paths diverge significantly from there.

Snails are part of the phylum Mollusca, a diverse group of invertebrates that also includes clams, squid, and octopuses. A key characteristic of mollusks is their soft, unsegmented body. Snails, specifically, are a type of mollusk called a gastropod. They possess a muscular "foot" on which they glide, secreting a layer of mucus to aid in movement and protect their soft body. Their most recognizable feature is the protective, coiled shell, which is an external skeleton they can retreat into for safety.

Insects, on the other hand, belong to the phylum Arthropoda, the largest phylum in the animal kingdom. This group includes animals like spiders, crabs, and centipedes. A defining feature of arthropods is their exoskeleton, a hard outer shell made of a substance called chitin. Unlike a snail's shell, an exoskeleton is segmented and must be shed and regrown as the animal gets larger. Insects are further classified into the class Insecta, which is defined by specific physical traits: a three-part body (head, thorax, and abdomen), three pairs of jointed legs, and a pair of antennae.

While both snails and insects are invertebrates, their fundamental body plans are distinct. A snail’s soft, single-bodied structure and protective shell are characteristic of mollusks, whereas an insect's segmented body, jointed legs, and chitinous exoskeleton are hallmarks of arthropods. Understanding these differences in taxonomy helps us accurately identify and categorize the vast diversity of life on Earth.

Fun Fact: A snail's rasping tongue-like organ, called a radula, is covered in thousands of microscopic teeth, which it uses to scrape and shred food.

Which phylum do snails belong to?

ArthropodaMolluscaInsectaGastropoda

What is the hard outer covering of an insect called?

RadulaShellExoskeletonMantle

What is a defining characteristic of all arthropods, according to the passage?

A three-part bodyA soft, unsegmented bodyA hard, segmented exoskeletonA protective coiled shell

Based on the passage, why are snails and insects not classified in the same group?

Snails have shells, while insects do notThey are in different kingdoms of lifeTheir fundamental body plans are differentThey live in different habitats

A scientist discovers a new animal with a soft, unsegmented body and a single muscular foot for movement. Which phylum is it most likely to be in?

InsectaArthropodaAnimaliaMollusca

According to the provided reading, which of these animals is most closely related to a snail?

A spiderA clamA grasshopperA millipede

Imagine you find a small creature with a head, a thorax, and an abdomen. It has six legs and a pair of antennae. Based on the passage, what is the best classification for this creature?

GastropodMolluskInsectArthropod

A student observes a beetle's hard outer covering and a snail's shell. What is the primary difference in how these two structures function for the animals' growth?

The beetle's covering provides more protectionThe snail's shell is shed, while the beetle's is notThe beetle's covering is shed and regrown as it growsThe snail's shell allows for faster movement