Invertebrates, Mollusks, Arthropods and Echinoderms

Science

A feeler on the head of a crustacean or insect

Antenna

A feeler on the head of a crustacean or insect. An antenna is a sensory organ used by animals to detect changes in their environment.

The opening at the end of the digestive tract where waste leaves the body

Anus

The opening at the end of the digestive tract where waste leaves the body. The anus is the body part that allows solid waste to exit the digestive system.

An invertebrate with an exoskeleton, jointed legs, and segmented body, like any insect, spider, crab etc

Arthropod

An invertebrate with an exoskeleton, jointed legs, and segmented body, like any insect, spider, crab etc. arthropod. An arthropod is an animal with a hard outer shell and multiple jointed legs.

Body plan composed of two halves which are mirror images of each other

Bilateral symmetry

Body plan composed of two halves which are mirror images of each other. Bilateral symmetry. In science, bilateral symmetry means that if you draw a line down the middle of a living organism, both sides look the same.

A circulation system in which blood flows within a network of vessels

Closed circulatory system

A circulation system in which blood flows within a network of vessels. Closed circulatory system. In a closed circulatory system, blood moves through a series of tubes called vessels, delivering nutrients and oxygen efficiently throughout the body.

Aquatic invertebrates with stinging cells, like a jellyfish

Cnidarian

Aquatic invertebrates with stinging cells, like a jellyfish. Cnidarians are simple aquatic animals that often have tentacles with stinging cells for capturing prey.

A marine invertebrate with an internal skeleton and a water vascular system, like a starfish

Echinoderm

A marine invertebrate with an internal skeleton and a water vascular system, like a starfish. Echinoderm. An echinoderm is a sea creature with a spiny skin and a system that uses water to help it move and feed.

An internal skeleton, it is made of bone and/or cartilage

Endoskeleton

An internal skeleton, it is made of bone andor cartilage. Endoskeleton. An endoskeleton is the framework inside the body that supports and shapes an organism, like humans or animals with bones.

The hard outer covering that protects some animals, like spiders

Exoskeleton

The hard outer covering that protects some animals, like spiders. Exoskeleton. An exoskeleton is a protective shell on the outside of an animals body.

An arthropod with three body segments, six legs, two antennae, and compound eyes

Insect

An arthropod with three body segments, six legs, two antennae, and compound eyes. Insect. Insects are small animals with a hard outer shell, three main body parts, and six legs.

An animal without a backbone

Invertebrate

An animal without a backbone is an invertebrate. Invertebrates are animals that lack a spinal column, like insects, worms, and jellyfish.

The immature form of an animal, it looks very different from the adult form

Larva

The immature form of an animal, it looks very different from the adult form. Larva. In simple terms, a larva is the early stage of an animal's life cycle, often looking nothing like the adult, and eventually transforming as it grows.

The respiratory organ that absorbs oxygen from the air and removes carbon dioxide from the blood

Lung

The respiratory organ that absorbs oxygen from the air and removes carbon dioxide from the blood. Lung. The lung is an organ that helps you breathe by taking in oxygen and expelling carbon dioxide.

An umbrella-shaped free-swimming organism, like a jellyfish or hydra

Medusa

An umbrella-shaped free-swimming organism, like a jellyfish or hydra. Medusa. A medusa is a stage in the life cycle of certain cnidarians, characterized by its bell-shaped, floating form.

Changes in form as an animal becomes an adult

Metamorphosis

Changes in form as an animal becomes an adult. Metamorphosis. Metamorphosis is a biological process where an animal undergoes significant physical changes from its early stages to adulthood, like a caterpillar turning into a butterfly.

An animal with a soft body and a muscular foot, it may also have a shell, like a snail or squid

Mollusk

An animal with a soft body and a muscular foot, it may also have a shell, like a snail or squid. Mollusk. A mollusk is a type of invertebrate animal, often with a soft body and sometimes a shell.

The shedding and replacement of an exoskeleton, skin or feathers

Molting

The shedding and replacement of an exoskeleton, skin or feathers. Molting is a natural process where animals like birds and insects shed old layers to grow and develop new ones.

A system in which blood moves through open spaces as well as vessels

Open circulatory system

A system in which blood moves through open spaces as well as vessels. Open circulatory system. In an open circulatory system, blood flows freely around the body's organs instead of being contained entirely within blood vessels.

A tube-shaped organism usually attached to a surface, it is a life stage of a cnidarian

Polyp

A tube-shaped organism usually attached to a surface, it is a life stage of a cnidarian. Polyp. A polyp is a small, sessile life stage of some marine animals like jellyfish and corals, often resembling a small tube with tentacles.

Body parts arranged in a circle around a central point

Radial symmetry

Body parts arranged in a circle around a central point. Radial symmetry. Radial symmetry is when an organism's body is organized around a central axis, like the spokes of a wheel.

A tonguelike organ with teeth in mollusks like snails

Radula

A tonguelike organ with teeth in mollusks like snails. Radula. The radula is a special organ in some mollusks used to scrape or cut food before eating.

Hollow tubes that end in suction cups, echinoderms use them to move and collect food

Tube feet

Hollow tubes that end in suction cups, echinoderms use them to move and collect food. Tube feet are small, flexible, and extendable appendages on the underside of starfish and sea urchins that help with movement and feeding.

A system of fluid-filled tubes in echinoderms like starfish

Water vascular system

A system of fluid-filled tubes in echinoderms like starfish. water vascular system. The water vascular system is a network of tubes used by echinoderms for movement, feeding, and respiration.