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An invertebrate is a species of animal which does not have a backbone, such as spiders, insects, mollusks, lobsters, and crabs. It is estimated that as much as 97% of all animal species are invertebrates.
See the fact file below for more interesting Invertebrate facts, or alternatively, you can download our comprehensive worksheet pack to utilize within the classroom or home environment.
Facts About Invertebrates
- An estimated 97% of animal species are invertebrates.
- Insects, annelids, mollusks, echinoderms, protozoa, crustaceans, and arachnids are all invertebrates.
- Invertebrates vary widely in size, from microscopic mites and almost invisible flies to the colossal squid, which can reach 30 β 33 ft (9β10 m) in size.
- The largest number of described invertebrate species are insects.
- Invertebrates are ectotherms (cold-blooded): they warm their bodies by absorbing heat from their surroundings.Β
- Most invertebrates spend at least some part of their life in water.
- However, some groups of invertebrates live solely on land. Common examples include worms, insects, snails, and spiders.Β
- These invertebrates need to have special structures to deal with life on land.
- Most invertebrates change form as they grow, going through a process known as metamorphosis.
- So far, more than 1.25 million species have been identified/described, most of which are insects.Β
Invertebrates share four common traits.
- They do not have a backbone.
- They are multicellular, meaning all the cells have different responsibilities in keeping the animal alive.
- They have no cell walls, like all other animals.
- They reproduce by two reproductive cells, or gametes, coming together to produce a new organism of their species.
There are two types of Invertebrates, terrestrial and marine.
Terrestrial invertebrates include:
- Spiders: Spiders are air-breathing arthropods that have eight legs, fangs generally able to inject venom, and spinnerets that extrude silk.
- Insects: Insects are invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body, three pairs of jointed legs, compound eyes, and one pair of antennae.
- Millipedes and Centipedes: Millipedes are a group of arthropods that have two pairs of jointed legs on most body segments. Each double-legged segment is a result of two single segments fused together. Centipedes are elongated metameric creatures with one pair of legs per body segment.
- Worms: Worms are small animals with a long, narrow, soft body without arms, legs, or bones.
- Landhoppers: Landhoppers are amphipod crustaceans that have a flattened body about 1 cm long. It jumps into the air when disturbed, similar to a flea.
- Slaters: Slaters (also known as woodlice, sowbugs, and pill bugs) are multi-legged, land-living crustaceans. They are scavengers and feed mainly on decaying organic matter.Β
Marine invertebrates include:
- Crabs: Crabs are crustaceans that typically have a very short projecting “tail”, usually hidden entirely under the thorax. They live in all the world’s oceans, in freshwater, and on land, are generally covered with a thick exoskeleton, and have a single pair of pincers.
- Corals: Corals typically form compact colonies of many identical individual polyps. Coral species are important reef builders that inhabit tropical oceans and have a hard skeleton.Β Β Β
- Sea anemones: Sea anemones are a group of predatory marine animals. Because of their colorful appearance, they are named after the anemone, a terrestrial flowering plant.
- Jellyfish: Jellyfish are free-swimming marine animals with umbrella-shaped bells and trailing tentacles. Jellyfish use their sting to capture prey and act as a defense mechanism.Β
- Sea stars and Sea urchins: Sea stars, sea urchins, feather stars, brittle stars, and sea cucumbers are all found in the marine environment in a range of habitats from intertidal surf beaches to the deepest oceans.
- Snails and slugs: Snails and slugs are similar animals. The main difference between them is that a snail has a shell and a slug does not. Snails and slugs belong to the group of soft-bodied animals called mollusks, which also includes squid.
Invertebrates have specialized eating habits
- Some species are grazers and eat phytoplankton or algae.Β
- Some prey on other invertebrates.Β
- Some feed on dead and decaying organic matter.
- They are opportunistic eaters, feeding on plants, animals, and decaying organic material.
- Some invertebrates feed on other invertebrates.
- They are also a vital source of food for birds, fish, and animals.Β
- Invertebrates serve as food for humans too. Who doesn’t love crustaceans like shrimp, lobster, and crab?Β Β
Invertebrates as Weird Food
Here are a few of the world’s weirdest foods that all happen to be marine invertebrates.
- Sea squirts:
- Sea squirts are potato-shaped organisms found in all seas.
- Most species inhabit warm, shallow tropical waters, usually near the coral reefs.
- They have a round, leathery, yellowish- or greenish-brown body and are potato-shaped
- They are eaten all over the world, including Japan, Korea, France, Italy, Greece, and Chile.
- They can be served raw, dried, fermented, salted, or cooked.
- Echiuran worms:
- Echiuran worms are more commonly known as spoon worms or penis fish.
- They live in burrows in soft sediment in shallow water, but some live in rock crevices or under boulders.
- More than 230 species have been described.
- Typically consumed raw, it is chewy, salty, and surprisingly sweet.
- Stalked Barnacles:
- These are well-known shelled crustaceans that live on docks.
- They use their “legs” to filter feed out of the water.
- They are also known as “goose-necked” barnacles because of the long, prominent stalk attached to the body sitting on top.
- In some places, Paris and Belgium, barnacles are quite expensive.
- They are usually boiled before eating.
Invertebrates Worksheets
This bundle contains 11Β ready-to-use Invertebrates worksheets that are perfect for students who want to learn more about an invertebrate which is a species of animal which does not have a backbone, such as spiders, insects, mollusks, lobsters, and crabs. It is estimated that as much as 97% of all animal species are invertebrates.
Download includes the following worksheets:
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- December Solstice
- Colors of Yule
- Solstice Facts
- The Sun Gods
- Yuletide Symbols
- Mapping Yule
- Thor: The God of Thunder
- Festival of Lights
- Photo Log
- Yule to Remember
Frequently Asked Questions:
Do invertebrates lay eggs?
All invertebrates lay eggs and the eggs of some species hatch into an adult and some enter into the larvae stage and then move into an adult.
Do invertebrates have bones?
Invertebrates don’t have any bones at all.
Do invertebrates have hearts?
Instead of a heart, invertebrate animals have a simple circulatory system. Many do not even have blood.
How many invertebrates live in the ocean?
Over 10,000 species of animals are found exclusively in aquatic (marine) environments.
Are dragonflies invertebrates?
Dragonflies are insects, therefore, they are invertebrates.
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Link will appear as Invertebrate Facts & Worksheets: https://kidskonnect.com - KidsKonnect, November 12, 2017
Use With Any Curriculum
These worksheets have been specifically designed for use with any international curriculum. You can use these worksheets as-is, or edit them using Google Slides to make them more specific to your own student ability levels and curriculum standards.