Videos

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  • I have been keeping these caddisfly larvae in an aquarium on the back porch.
  • I hope to raise them to adults which are easier to identify to species.
  • During a cold snap a layer of ice formed on the water surface in the aquarium.
  • At night I noticed that the caddisfly larvae would crawl about on the undersurface of the ice.
  • They appeared to be feeding.
  • What could they be eating on the undersurface of the ice?
  • Think about the debris that floats up from a stream or lake bottom and gets trapped under the ice.
  • They have been identified as belonging to the genus Lenarchus.
  • According to the literature these larvae feed on organic sediments.
  • Colonies of aphids may develop near the top of fireweed plants.
  • To find them look for darkish areas on the plants.
  • These are often tended by red ants which eat the sugary honeydew excreted by the sap-feeding aphids.
  • The ants typically stimulate the aphids with their front legs which causes them to excrete the honeydew.
  • The ants then lap up this sugary sap.
  • The ants generally protect aphids from insect predators.
  • What would be the main benefit for both the ants and aphids for this behavior?
  • This relationship between ants and aphids is termed mutualistic i.e. the ants get food, and the aphids get protection.
  • For more information open up Natural Connections in Alaska and go to page 30.
  • juvenile fish living in Alaska's streams often concentrate together in ice-free areas during winter
  • this is interesting because at other seasons they are highly territorial
  • spring-fed areas in some streams may be critical to the overwinter survival of these fish
  • at Hood Bay creek on Admiralty Island we discovered most of the young coho and Dolly Varden migrated upstream to spring water areas for the winter
  • identification and protection of these special areas may be important to their survival, especially in cold winters when most of the stream is frozen
  • This video shows a gathering of juvenile Dolly Varden in a stream in Juneau Alaska.
  • An American Dipper dives over them and they swim rapidly away.
  • American Dippers will catch and eat juvenile Dolly Varden so their reaction is understandable.
  • Juvenile Dolly Varden are normally very highly territorial and at these ages only aggregate like this in Winter.
  • What would be the benefits of coming together in a group during winter?
  • Of interest this video shows them hovering around a pile of woody debris in the stream.
  • Why would they do this?
  • Think about camouflage, protection, and less current.
  • I read one study that indicated woody debris in streams may be a little warmer.
  • This video includes all species of chickadees found in Alaska.
  • The song Chickadee dee dee was created and played by John Palmes
  • For information on chickadees look at Chickadees by Mary Willson
  • This happened near the headwaters of a stream in Juneau.
  • This stream is spring-fed and the goshawk is bathing in one of the springs.
  • Many other streams in Juneau had layers of ice on them and were several degrees colder.
  • This is a good example of the value of springs for creatures in Alaska.
  • Why do birds need to bathe?
  • In Alaska these Harlequin Ducks nest along some of our fastest flowing streams.
  • This is quite unusual for ducks to nest in this type of habitat.
  • What would be some of the advantages for doing this?
  • These ducks feed heavily on aquatic insects while in these streams.
  • They may do this by swimming upstream and turning over stones with the top of their bill and grabbing the insects that live under them.
  • What other creatures in Alaska feed on and even depend on aquatic insects (in the aquatic stage)?
  • During winter in Juneau I often notice a variety of insects on the snow.
  • This seems to happen mostly when the temperature rises above 32 degrees for a short period.
  • Why would an insect run about on the snow during winter?
  • It could be for mating -- easier to find a mate with fewer species flying about -- less birds about to eat them.
  • Some look for prey to eat.
  • Springtails use the fairly flat snow to move from one habitat to another -- they apparently orientate on the sun or dark horizon to go in a constant direction.
  • It is fun to lay down on the snow and watch the tiny insects moving about and to think about why.
  • The following is from Aquatic Insects in Alaska by John Hudson, Katherine Hocker and Robert H. Armstrong
  • One of the biggest dangers to living tissue is ice.
  • Freezing binds up water that is essential to life, and sharp ice crystals pierce cell walls, damaging or destroying them.
  • But many aquatic insect larvae such as caddisflies in Alaska can survive being frozen into ice.
  • When the ice melts, the insect comes "back to life."
  • How do they do it?
  • They build up high concentrations of sugars or sugar alcohols that serve as antifreeze within their cells. Ice may form in the fluid outside the cells, where there is no antifreeze, but there it can't bulge the cells out or puncture their critical membranes.
  • It is fun to come across a creature you have never seen before and take its photograph.
  • Then with the help of the internet, books, or people who study these creatures you can usually find out what it is.
  • Once it is identified then you can try to find information about its behavior, habitats, life history etc.
  • I think photography can really help us learn about nature.
  • It was exciting to learn that this insect, which I had never seen before, was a sawfly.

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