Sensillum facts for kids

A sensillum is a tiny sensory organ found on arthropods. Arthropods are creatures like insects, spiders, and crabs. Sensilla (that's the plural of sensillum!) help these animals sense the world around them.

Most sensilla stick out from the cuticle, which is the tough outer skin or exoskeleton of an arthropod. Sometimes, they can be found hidden inside or under the cuticle. Each sensillum contains two or three special cells called sensory neurons. These neurons are like tiny wires that send information to the arthropod's brain.

What Are Sensilla?

Sensilla are super important for arthropods. They are how these animals smell, taste, touch, hear, and even sense temperature. Think of them as the arthropod's eyes, ears, nose, and fingertips all rolled into tiny structures!

Where Do You Find Sensilla?

Sensilla can be found all over an arthropod's body. They are very common on:

• Antennae: These are the feelers on an insect's head. They are packed with sensilla for smelling and touching.
• Mouthparts: Sensilla here help arthropods taste their food.
• Legs: Some insects can taste with their feet!
• Wings: Certain sensilla on wings help with flight control.
• Body surface: Many sensilla are spread across the body to detect touch or changes in air.

How Do Sensilla Work?

Each sensillum is made up of a few key parts:

• Outer part: This is the part that sticks out, like a hair, cone, or plate. It's connected to the outside world.
• Sensory neurons: These are the nerve cells inside the sensillum. When the outer part senses something (like a smell or a touch), the neurons get excited.
• Support cells: These cells help the neurons do their job and keep the sensillum healthy.

When a sensillum detects something, the sensory neurons send an electrical signal. This signal travels along the nerves to the arthropod's brain. The brain then figures out what the signal means, like "that's a tasty leaf!" or "something just touched me!"

Types of Sensilla

There are many different kinds of sensilla, each designed for a specific job.

What Sensilla Help Arthropods Smell and Taste?

• Chemosensilla: These are the most common type. They are like tiny noses and tongues. They have pores (small holes) that let in chemicals from the air or from food.
  • Olfactory sensilla: These detect smells (like a dog's nose). They are often found on antennae.
  • Gustatory sensilla: These detect tastes (like your tongue). They are usually on mouthparts or legs.

How Do Arthropods Feel and Hear?

• Mechanosensilla: These sensilla respond to touch, pressure, and movement.
  • Tactile hairs: These are simple hairs that bend when touched, sending a signal.
  • Proprioceptors: These help the arthropod know where its body parts are in space, like how you know if your arm is bent or straight without looking.
  • Chordotonal organs: These are special mechanosensilla that can detect vibrations, including sound. Crickets use them to hear each other's songs!

What Sensilla Help Arthropods Sense Temperature?

• Thermosensilla: These detect changes in temperature, helping arthropods find warm places to live or avoid too much heat.

How Do Arthropods See?

While arthropods have compound eyes for seeing images, some sensilla can also detect light. These are called photosensilla. They might not form clear images, but they can tell the difference between light and dark.

Why Are Sensilla Important?

Sensilla are vital for an arthropod's survival. They help them:

• Find food and water.
• Detect predators or danger.
• Find mates for reproduction.
• Navigate their environment.
• Control their movements, like flying or walking.

Without these amazing tiny organs, arthropods wouldn't be able to do all the incredible things they do!

Images for kids

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  A robot, like an arthropod, uses sensors to understand its world.