How to live without a heart or a brain - Lessons from a Jellyfish

Jellyfish are ancient creatures related to coral and sea anemones, dating back 500 million years. Despite lacking a brain and heart, they thrive in various environments. Their nerve net allows them to sense and respond to their surroundings. Some jellyfish have advanced sensory structures like ropalia and eyespots. They absorb oxygen through their ectoderm and store it in the mesoglia, allowing survival in low-oxygen waters. Their simple digestive system breaks down food in the gastrovascular cavity. Jellyfish complexity offers insights into the evolution of nervous systems.

What is one reason jellyfish are considered ancient creatures?

• They have a complex brain.

• They are related to mammals.

• Their ancestors date back 500 million years.

• They have a complete digestive system.

How do jellyfish sense their environment without a central nervous system?

• With the help of a heart.

• By using a complex brain.

• By relying on other sea creatures.

• Through a nerve net spread throughout their body.

What is the function of ropalia in jellyfish?

• To store oxygen.

• To pump blood throughout the body.

• To sense light and maintain balance.

• To help them digest food.

How do jellyfish meet their oxygen needs without a heart?

• By absorbing oxygen through their ectoderm.

• By storing oxygen in their stomach.

• By using lungs.

• By filtering oxygen from food.

What is the primary component of a jellyfish's body structure?

• Bone and muscle.

• Mesoglia, a jelly-like fluid.

• Thick skin layers.

• Cartilage.

How do jellyfish digest their food?

• By absorbing nutrients through their skin.

• Through the gastrovascular cavity.

• By using a liver and pancreas.

• With a complete digestive system.

What evolutionary significance do jellyfish hold?

• They have the most complex nervous system.

• They represent nature's first draft of a nervous system.

• They are the first animals to develop a brain.

• They are the only animals with a nerve ring.