Nenes, Anoles and Dewlaps

Here's a guest post from our colleague Margriet Ruurs, written when she was visiting Hawaii in the winter. There she discovered that Hawaii is home to both Nene geese and anoles!

Ever heard of a Nene goose or an anole and his dewlap? I hadn’t until I traveled to Hawaii.

I love learning new things and animals never cease to amaze me. Each continent has amazing animals that are unique to that part of the world.

We’ve all heard of kangaroos and koalas in Australia. We know that North America has moose and bears and Canada geese.

Strange geese

But have you ever heard of Nene geese?

I hadn’t until I spotted this sign along the road on Moloka’i, a small, sparsely populated island. Turns out that the Nene goose is only found on the Hawaiian islands and is quite rare.

Stranger lizards

If you have been to tropical places, you may have spotted iguanas, geckos or other types of intriguing lizards.

I’m sitting in a garden in Hawaii and notice a little lizard running along the wall. I marvel at how their toe pads are equipped with tiny little hooks that allow them to run straight up the wall.

This little guy is about 12 cm long. It darts along a stone wall on little legs with a long tail and a flicking tongue. Then he stops so I can get a good look at him. But, what I think is just another little gecko, turns out to be quite something else.

Researching this cool little guy teaches me that this is a lizard, but not a gecko at all. It’s a brown, male anole.

A what?

I had never heard of anoles. While geckos and anoles are both lizards, they have evolved in different ways. Anoles didn’t appear on the scene until roughly 150 million years after the gecko. Both have adhesive toe pads that allow them to run straight up walls.

Geckos can live in dry, rocky areas while anoles prefer living among more trees. While they can live near each other, they are competitive. Anoles are active during the day, while geckos are more nocturnal.

Strangest...

But the coolest thing I notice about my little anole friend, is his dewlap.

His what?!

A dewlap is a flap of skin underneath the lizard’s chin, which he can extend and retract. It’s not an air sac, just a flag he waves when staking out his territory or when trying to attract a female. He also waves it to warn off an intruding gecko.

Watch him raise his warning flag in the sequence of photos below:

©Photos copyright: Margriet Ruurs

You can learn more about Nene geese here: http://www.ducks.org/hunting/waterfowl-id/hawaiian-nene-goose

For more details on anoles, click here: http://www.anoleannals.org/2018/03/26/anoles-versus-geckos-the-ultimate-showdown/

Margriet Ruurs is the author of Amazing Animals (Tundra Books). You can find out more about her work at her website, www.margrietruurs.com

Could There Be a Volcano Near My House?

By Adrienne Montgomerie

Well, it depends on where you live. There are certain areas on the planet where you might want to set up sensors. Most of those are out in the Pacific Ocean. If your house is in North America, I’m going to say you’re basically volcano free. Unless you’re on the west coast. And only a handful of volcanoes have been active in North America in the last 150 years. Here’s why.

How do volcanoes form?

Deep beneath the Earth’s hard crust is a core of rock so red hot that it has melted. It’s a little like the melted mozzarella in a cheese stick. Except that in the Earth, the molten rock is swirling and rising up, unlike the cheese. This molten rock breaks through the crust mostly at natural seams where continents meet (tectonic plates, actually). That’s why we find some on the west coast of America.

Earth’s crust is about 30 km thick on the continents. It would take you just over 6 hours to walk that distance. In some places on the ocean floor Earth’s crust is thinner, about 5 km thick. At hot spots in the thin crust, molten rock breaks through and spews out onto the surface as lava. As the lava cools and builds up on itself over years and years, it makes a mountain. Because the lava keeps flowing up and out of the Earth in that mountain, we call it a volcano.

The Hawaiian Islands were formed by lava bubbling up over many thousands of years and cooling into island-sized mountains. The tallest of the Hawaiian Islands is actually several hundred metres taller than Mount Everest, if you measure from its base at the bottom of the ocean.

Scientist believe that the hot spot where lava is bubbling up stays in one place as the crust slides extremely slowly over top of it. This is why there is a whole chain of islands in Hawaii. As the crust moves over the hotspot, a new island starts forming. 

Lava flows into the sea, growing the big island in Hawaii in 2006. By Jennifer Williams, CC BY-SA 2.0

Is it dangerous to live near a volcano?

Lots of people live near a volcano. Does that sound crazy? I mean, when it erupts, a volcano can spew boiling hot rock chunks as big as a refrigerator high into the sky. It can send 1200 °C lava flowing down the hillside for many kilometers. The hot gases and ash that get blown out with the melted rock can spread clear around the globe, causing destruction in its path.

When Mt St Helens in Washington erupted in 1980, it caused a medium-sized earthquake and spread ash all the way around the world over two weeks’ time. Besides the many bridges, homes and roads that were destroyed, 57 people were killed by the eruption.

When the Eyjafjallajökull volcano in Iceland erupted in 2010, planes could not fly in all of Europe for 8 days because of the ash cloud. Safety officials were afraid the hot ash would damage engines and make the planes crash. Flights in Europe were grounded because of ash several more days over a month.

Why do people even live near volcanoes?

The thing is, volcanoes don’t erupt violently that often. Even the world's most active volcano is just slowly leaking lava down its sides and burning surrounding neighborhoods to the ground. That is the Kilauea volcano in Hawaii and it has been erupting constantly for 35 years. But the Yellowstone volcano only erupts every 700,000 years.

Volcanoes tend to be in very lush environments. Sometimes the environment is lush because of the volcano and all the minerals that lava brings to the surface. That may have attracted people’s ancestors to the area, and they stayed. Some people live near volcanoes because it is affordable—cheap homes because they risk destruction.

In many cultures, volcanoes are thought to have spiritual power or importance. They are expressions of the gods, and bring luck and prosperity as well as destruction. Some people may live near volcanoes for that reason.

Scientists live near volcanoes so they can study them. It’s extremely dangerous, and there are many stories of volcanologists dying at work.

A USGS department geologist takes the temperature of a lava flow on Mt. Kilauea in 1984. Public domain.

Can I visit a volcano safely?

There are about 1,500 volcanoes in the world that could be active. Only about 500 have erupted in recorded history. In Hawaii, you can tour the lava tubes created by lava flows. You can visit the Greek island of Santorini that is still an active volcano with 13,600 people living on it. It has had very small eruptions that build up its sides over the last 70 years. And there are at least 1000 others you can climb on. Take a look at the list of volcanoes and think about which one you’d like to visit.

Santorini, Greece, is built on the rim of a very old volcano. You can tour the centre that is an island now. By Pedro Szekely, CC BY-SA 2.0

Ancient Fish Farming in Hawaii

By Shar Levine

What do science writers do when they go on vacation to the Big Island of Hawaii? If you are Shar Levine and Leslie Johnstone, you look for science at the beach.  At 'Anaeho'omalu Bay, or "A" Bay as the locals call it, the pair spent an afternoon at the anchialine ponds located between the Marriot Hotel and the beach.

Anchialine ponds are only found on two of the Hawaiian islands, Hawaii and Maui. These small inland ponds are found close to the ocean but are not connected to the surface of the sea. Salt water from the ocean seeps through the ground where it is mixed with fresh water flowing from the mountains. The pond is less salty than the ocean, but more salty than fresh water from a stream. The mixture of the two creates a unique "brackish" water for the fish living in the pond.

Anchialine Ponds, with "A" Bay in background

Hiding in the algae and water plants along the sides of the pond you can see shrimp, crabs, mollusks and tiny fish.  Much to the delight of tourists, an eel will sometimes poke its head out from the lava rocks in the waters just below the bridge connecting the pond to the beach. In the deeper section of the pond, large fish including amberjack and barracuda patrol the waters. The salinity of the pond varies with the depth and temperature of the water. Creatures who live in these waters are different from their relatives who live in the ocean and scientists are interested in studying how the fish have adapted to survive in this environment.

Types of fish found at "A" Bay pond

The ancient Hawaiians used these ponds as an early form of fish farming. There was very little work for the people to do. Small fish would enter the pond through a gated channel from the ocean to an outer pond. From there, the fish would thrive on algae and plants growing in the waters. The fish soon became too big to leave the pond through the gate. When the fish were adults,  they could easily be caught in a net and served for dinner.

The ponds form their own ecosystems. Here's how the food chain works: