SCIENCE with Ms Lun
Sounds of Aotearoa
New Zealand's outdoors is full of natural sounds from the crashing of waves, bird song, insects to underwater sounds.
Birdsong & calls
There are two websites with good recordings of birdsongs:
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DOC (Department of Conservation /Te Papa Atawhai) : there is a page with recordings
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NZ Birds Online: you will have to search by individual bird
Insect sounds
Here's a couple of insects you'll be familiar with, especially in the warmer months. In the YouTube videos, you can also see how the sounds are made. For more information about how the sounds are made, scroll to the section towards the bottom of this page.
Underwater sounds
Kina or sea urchin
(Evechinus chloroticus)
Left: live kina. Right: kina shell
They make noise when they eat
NZ snapping shrimp or
kowhitiwhiti moana
(Alpheus novaezealandiae)
The large claw snaps
In 2008, Dr Craig Radford and his team of marine biologists studied our oceans for animal noise. They found four marine animals. You can read more in an article called "The noisy reef" featured on the Science Hub website (probably more suited to Year 5+).
The video below is from that article.
Red gurnard or kumukumu
(Chelidonichthys kumu)
These fish grunt, groan and growl!
John Dory or kuparu
(Zeus faber)
Woof! Makes barking sounds.
How are the sounds made?
In this section, we will learn how some of the animals make their distinctive sounds.
Birds
Like humans, birds have a vocal organ. In birds, it is called the syrinx.
The syrinx:
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is a bony structure located at the bottom of the trachea. (Our vocal chords are at the top of the trachea)
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sometimes has a surrounding air sac
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is split in two. The membrane separating the two sides is called the tympanum (or tympanic membranes).
As the bird exhales (breathes out), air going through the syrinx causes the tympanum to vibrate. This creates sound. The pessulus is a small, delicate piece of cartilage.
Because the syrinx has two sides, they can work independently. This enables birds to produce different sounds at the same time!
Cricket
How a cricket chirps :
basic version
By rubbing its wings together, sound is made. This is called stridulation.
Crickets belong to the order Orthoptera (includes locusts, grasshoppers and wetas).
Crickets do not vocalise their sounds like us. Instead they use a process called stridulation.
They rub their wings together really fast. On the underside of the lower wing, there is a row of bumps called a "file". On the upper side of the other lower wing is a sharp edge or "scraper". When they are rubbed together, it produces a chirping sound. Only males chirp. They do this to attract a female.
File and scraper
Cicada
How a cicada chirps : basic version
Using a special part on each side of its exoskeleton called a tymbal, the cicada makes noise. Muscles pull the tymbal in and out very quickly.
Cicadas belong to the order Hemiptera (includes aphids, leaf hoppers and shield bugs). They don't use stridulation like crickets. Instead, they have
a special structure on each side of their abdomen called a tymbal. It is corrugated with rib-like structures. The tymbals are attached internally to muscles. When the muscles contract, the tymbals buckle inward and when the muscles relax, the tymbals unbuckle and a sound is made. Only males chirp. They do this to attract a female.
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Tymbals can contract up to 300 times per second!
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Some species of cicadas are as loud as 100dB
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A NZ species of cicada (Amphipsalta cingulata) also makes clicking or clapping sounds by tapping their wings on the branch (or whatever) they are sitting on.
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The Maori name kihikihi wawa means "to roar like the sound of heavy rain"
Cicadas are noisy insects. There is a very good video on the National Geographic website called "Today I learned that Cicadas can damage your ears."
Kina (Evechinus chloroticus)
How a kina makes noise :
basic version
When their mouth parts scrape algae off rocks, the sound is made louder by their body.
Kina are noisiest at dusk when they feed. They have a special feeding apparatus called an Aristotle's lantern. There are 5 calcium carbonate teeth and 5 plates and a fleshy tongue-like structure inside.
The kina shell (also called a test) acts as an amplifier (makes the sound louder) for the vibrating air within it when it eats. Scientists describe the shell as acting like a Helmholtz resonator (did you see this mentioned in the video in the Underwater Sounds section?).
This is similar to when you blow across the top of an empty bottle and you hear a loud sound.
Who was Aristotle?
He was a scientist who lived 384 years BC. He was the first person to describe the structure, ecology and diversity of sea urchins. His findings were misinterpreted. He had described the whole urchin as resembling a lantern, however, zoologists first interpreted his findings as meaning the feeding apparatus resembling a lantern.
NZ snapping shrimp (Alpheus novaezealandiae)
How a snapping shrimp makes noise :
basic version
When their large claw snaps together, a super-heated water bubble is forced out. This pops when it bursts. It also stuns the shrimps prey (food).
Snapping or pistol shrimps are found worldwide. The New Zealand species is only 2-3 cm long. Snapping shrimps have asymmetrical claws, meaning one claw is bigger than the other.
The claw has two parts: a flat anvil and a concave scoop. When the claw snaps very fast, the enormous force super-compresses the water caught between them. The water heats up to about 4000°C and expands. A low pressure bubble shoots out. As it decompresses, it expands and bursts.
There is a video showing how the snapping shrimp
uses its claw.
Snapping shrimp facts
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The "snap" is very fast: only 10 nanoseconds
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The sound generated can be as loud as 218dB
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If the big claw is lost or damaged, the other claw will grow bigger
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In World War II, submarines would "hide" in areas with lots of snapping shrimps to avoid enemy surface tracers
Discover Maori musical instruments
There are many taonga puoro (Māori musical instruments) such as:
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pūtātara (shell trumpet)
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pūkāea (war trumpet)
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karanga weka (used to imitate the call of the weka bird)
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pūtōrino (bugle flute)
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bone kōauau (flute)
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hue (vegetable used for various instruments)
Visit Te Papa to see images and hear recordings of some taonga puoro (Māori musical instruments).
The porotiti is another instrument. Made from a variety of materials (pounamu, bone or wood) it is spun on two cords to make a humming sound.
The porotiti shown below is from the Te Ara (the encyclopedia of NZ) website
