Page 102 - BBC Wildlife Volume 36 #04

Q&A

Q MARINE BIOLOGY
Q BIOLOGY
Do octopuses ever What is the point

live together? of cuckoospit?

Up to 16 individuals A The white, foamy nests produced by
A Yes. A few years ago, rub tentacles quite It’s thought that plant bug nymphs are whipped up using
happily in Octopolis.
diversonAustralia’s Octopolis was a mixture of air released ffrom respiratory
i t
east coast discovered founded when openings (known as spiracles) and
a
dozens of a 30cm object – liquid exuded from the anus. Strangely,
n
octopuses living possibly made of the foam makes these little green
t
together and metal – landed insects more conspicuous rather
getting along on a scallop bed. than less, and doesn’t
– more or less. A few pioneers seem to contain toxins
The finding, moved into this or repellents. It may still
named impromptu provide a physical defence
c
Octopolis, shelter, against insect predators,
came as a feeding on the or prevent dehydration
huge surprise, surrounding or overheating, though
because these are shellfish. The there is littleevidence
notoriously anti- discarded shellsthen for any of these possibilities.
t
social creatures that provided ideal material What has been shown is that the
t
usually live alone. for fellow settlers to create foam shields the bugs from
o
Hours of diving and footage dens, allowing the ‘city’ to expand. the harmful effects of UV
V
from cameras rigged around Octopolis Octopolis is unusual, but not unique. radiation in bright sunlight.
h
are revealing complex behaviour: A second site nearby, known as Octlantis, The smaller the bubbles, the
residents tussle and fight (but don’t kill is home to a similar throng,showing that more effective the sunscreen. Cuckoospit:
r
clearly not for
each other), and communicate via colours these molluscs are not as unneighbourly Stuart Blackman camouflage.
flickering across their skins. as we previously thought. Helen Scales
Only male
humpbacks
‘sing’, perhaps to
attract a mate or
intimidate rivals.

Octopus: cbimages/Alamy; cuckoosp t: Gianpiero Ferrari/FLPA; humpback: David Fleetham/naturep .com

Q CETACEANS
Can whale

song ever A Whales and birds live in human ear (the thrush's linking factor could be that

resemble contrasting environments song resembles a cross both species sing alone.
and create sound in very
In contrast, the social
between that of a robin and
birdsong? different ways. Surprisingly, a blackbird, while that of the calls of killer whales have
there can be similarities,
a clustering structure like
whale comprises an eerie
evident when you compare series of groans, moans and that of human conversation
the songs of the hermit roars), if you look at the way and jazz – a genre of music
thrush and humpback whale. the sounds are clustered often dubbed a ‘conversation
Though the two vocalisations together in time, the two are between musicians’.
sound very different to the actually quite similar. The Liz Kalaugher

102 BBC Wildlife April 2018