Hydroids: Portuguese Man o' War and Velella velella (By-the-Wind Sailor)

A set of Q&A flashcards covering the key concepts about pelagic colonial hydrozoans (Portuguese man o' War and Velella velella) from the notes.

What are the Portuguese man o' war and Velella velella in biological terms?

Colonial hydrozoans with gas-filled floats and sails.

What is the common name of Velella velella?

By-the-wind sailor.

What structure allows these organisms to float, and how does it differ from Physalia?

A kitinized structure with some gas, not inflated like Physalia.

How do these organisms respond to being handled?

They can be handled with ease without a massive reaction.

Are these organisms solitary or colonial?

They are colonial; Velella has a vessel with a central nourishing polyp, blue tentacles, and reproductive polyps working together.

What do polyps beneath the vessel do?

They ballast the sailboat.

What do Velella feed on?

Fish eggs, larvae, or small shellfish.

How do they hunt and process prey?

They use stinging tentacles to capture prey and haul it into the central cavity.

Are Velella closely related to jellyfish?

Yes, they are close cousins of jellyfish.

How are Velella colonies structured?

They are colonies of polyps located under the vessel, including a central nourishing polyp, blue tentacles, and reproductive polyps, all working together.

How are their larvae produced and dispersed?

Reproductive larvae hatch as microscopic jellyfish (male and female); after 1–2 weeks they grow into adult pelagic vessels; dispersal depends on wind direction.

What is the genetic and origin relationship among individuals in a Velella colony?

They are genetically identical and originate from a single polyp.