• Definition: Signalling chemicals = substances used for communication within the body.
• Fact: Such systems, particularly using hormones & neurotransmitters, have evolved over and over again. 🦠➡️🐒
• Requirements of a Signalling Chemical:
  • Unique Shape & Properties: So that receptors can identify them (Think of it like a lock and key, only the right key fits!)
  • Size & Solubility: They need to be tiny & soluble so they can easily travel around.

• Meet the Crested Newt (Triturus carnifex)
  • Male's Moves
    • Sniff, Sniff: First, he sniffs the female's head. (Kind of like a "Hello!")
    • Tail Wave: Waves his tail toward her head. (It's like saying "Hey, check this out!")
    • Tail Hit: Bonks her on the head with his tail. (Kind of a risky move!)
    • The Gift: Places sperm next to her.
  • Female's Reaction
    • If she's interested, she stays still & then picks up the sperm.
    • If she's not feeling it, either of them can just walk away.

Real-World Connection: This is like a dance between two people! But remember, it's all about reading signals.

• How can the male know he's wooing the right species of newt? (Hint: Maybe the sniffing? 🤔)
• How does the female decide if the guy is Mr. Right or Mr. Not-So-Right? (Could be the dance moves... or tail bonks!)