Q 01/05

How many hearts does an octopus have, two of which serve only to push blood through the gills?

A) Three

B) Four

C) Six

D) Eight

Answer · why

A) Three

Three hearts share the work, and the main one stops beating whenever the octopus swims, which is why it loses energy quickly and mostly crawls.

Q 02/05

Where in its body does an octopus keep about two-thirds of its neurons, rather than in its brain?

A) In its skin

B) In its arms

C) In its eyes

D) Along its gut

Answer · why

B) In its arms

In its arms, which can move and sense largely on their own without waiting for orders from the brain; even a severed one still responds to touch.

Q 03/05

Which metal, in place of the iron in human blood, carries oxygen in octopus and squid blood?

A) Zinc

B) Cobalt

C) Copper

D) Nickel

Answer · why

C) Copper

Copper sits at the core of hemocyanin, a protein dissolved straight into the plasma that moves oxygen better than hemoglobin does in cold, oxygen-poor...

Q 04/05

Which small cephalopod of Pacific tide pools carries enough venom to kill more than 20 adult humans?

A) Mimic octopus

B) Common Sydney octopus

C) Blue-ringed octopus

D) Day octopus

Answer · why

C) Blue-ringed octopus

Blue-ringed octopus venom contains tetrodotoxin, the nerve poison also found in pufferfish, and no antivenom exists; victims pull through only if some...

Q 05/05

Which cephalopod of deep Antarctic waters, bearing swiveling hooks, is the heaviest invertebrate alive?

A) Giant squid

B) Colossal squid

C) Humboldt squid

D) Vampire squid

Answer · why

B) Colossal squid

Colossal squid can weigh about 495 kg and have the largest eyes documented in the animal kingdom, each roughly the width of a dinner plate at 27 to 30...