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The Eel-tailed Catfish (Tandanus tandanus)

Last week, I wrote about the great builders of the animal world, the beavers. But of course all sorts of other creatures build things.  The Eel tailed catfish (Tandanus tandanus) lives in the Murray-Darling river basin of Eastern Australia where the creatures’ nest-building habits are costing them dearly.

The eel-tailed catfish is from the family Plotosidae (in fact it is a close relative of the striped eel catfish) and like other family members its most distinctive feature is a continuous fin margin surrounding the posterior half of their bodies—aka an eel tail!  These catfish prefer to live on the gravel or sand at the bottom of lakes or slow-moving rivers.  They eat crayfish, yabbies’, worms, mollusks, insect larva, and other smaller fish.

An eel-tailed catfish nest (the parent is in the middle)

A week or two before spawning, pairs of eel-tailed catfish build nests for their eggs. The fish construct these torus-shaped structures out of sand and pebbles and, once the female lays the eggs, one or both parents stay with the nest to guard it and to aerate the eggs until they hatch.  Unfortunately, because of drought and agriculture, the Murray basin is rapidly drying out and silting up.  As the pebbles and coarse sands which the fish use for nests are smothered with slimy silt, the species has been declining.  Additionally, eel-tailed catfish are being out-competed by invasive carp which were introduced in a hare-brained aquiculture scheme.

A Dugong and Diver (photograph by Duane Yates)

There are about 120 living species of marine mammals (although that total may tragically become much smaller in the very near future).  Of this number, only one species is herbivorous.  The mighty dugong (Dugong dugon) is the last animal of its kind, a gentle lumbering remnant of the giant herds of sirenian grazers which once graced the world’s oceans. Dugongs are distinct from the three extant species of manatees (the world’s other remaining sirenians) in that they never require fresh water at any point of their lives.  Additionally dugongs possess fluked tails in the manner of dolphins and whales.

Dugong Range

Dugongs live in shallow tropical waters of the Indian Ocean and the Pacific Ocean.  They range from Madagascar to the Philippines, but are only common along the north coast of Australia (where conservation efforts and a limited human population have allowed them to live in peace).  Dugongs can swim in deep oceans for a limited time, but prefer to stay on continental shelves where they can feed on seagrass and marine algae.  Their all-salad diet does not prevent them from growing to substantial size: some individuals have been known to reach more than 3.5 meters in length (11 feet) and weigh over 950 kilograms (nearly a ton).  Although Dugongs can live more than seventy years, they reproduce extremely slowly.  Females gestate for over a year and then suckle their calf for around 18 months. Calves may stay with their mothers for many years after being weaned and need almost contact with their mothers for security and affection until they are almost grown. Young dugongs swim with their short paddle-like flippers, but adults use their tail for propulsion and only steer with their flippers.

Dugong and Calf

Dugongs have a variety of vocalizations with which they communicate.  Usually they live in small family units.  Great herds are not unknown but  seagrasses do not grow in sufficient quantity to support such numbers together for long.

Like the other sirenians, Dugongs have dense bones with almost no marrow (a feature known as pachyostosis).  It has been speculated that such heavy skeletons help them stay suspended just beneath the water in the manner of ballast.  The lungs of dugongs are extremely elongated, as are their large elaborate kidneys (which must cope with only saltwater).  Additionally, the blood of dugongs clots extremely rapidly.

Dugongs face a number of natural threats, particularly storms, parasites, and illnesses.  Because of their large size they are only preyed upon by alpha predators such as large sharks, killer whales, and salt-water crocodiles.  As with other marine animals, the greatest dangers facing dugongs come from humankind.  For millennia Dugongs have been hunted for meat, oil, and ivory. Traditional medicine from various portions of their range (wrongly) imputes magical properties to parts of their bodies. Worst of all, dugongs are frequent victims of boat collisions or are killed as by-catch by fishermen trying to catch something else.

Close-up of a Dugong (Julien Willem)

Wild Turkey Poults

During February and March, tom turkeys beguile hens with their magnificent gobbles and vivid visual displays. Shortly thereafter the hens begin nesting. Not only are turkey eggs larger than chicken eggs, they are covered with delicate brown speckles and tend to have a more acute taper on one end than chicken eggs do.  The turkey hen constantly broods her eggs leaving only briefly to eat.  When she is sitting on her nest, the hen is extremely vulnerable to predators.

Turkey Eggs

A month later, turkey poults emerge from the eggs.  The tiny poults punch open the egg with egg teeth (sharpened ridges on the beak which quickly vanish as the young turkeys begin to grow). Wild turkey poults leave the nest about a day after they hatch.

Bourbon Red Turkey Poults on a farm

Wild turkeys face a terrifying host of predators including bobcats, raccoons, skunks, opossums, foxes, coyotes, armadillos, weasels, crows, owls, hawks, bald eagles, and a variety of snakes. To cope with this list wild poults quickly develop limited flight capability and begin roosting in trees two weeks after they hatch.  Domestic turkey poults need substantial warmth to thrive and must be kept under a hot lamp and never given cold water.  They need medicine supplements to prevent infection from chicken diseases and special calcium supplements to make up for the minerals which their wild cousins get from the bugs and arthropods which make up the bulk of their diet.

Day old Narragansett Turkey poults (photo by Cackle Hatchery)

One of the most endearing traits of poults is the way in which they imprint on their mother and then follow her around.  This trait is identical in domestic turkeys: when we ordered poults during my childhood, the little fluffy birds imprinted on me.  Thereafter they would follow me around the barnyard peeping–which was very cute but made me worry about their well-being (imprinting being a two-way street).  The young turkeys were affectionate and endlessly amusing.  Indeed the Aztec trickster god Tezcatlipoca was strongly associated with turkeys because of their playful tricks and the deity was said to sometimes manifest as a turkey.  In the picture below, Tezcatlipoca even looks a bit like a strutting Tom.

A Turkey and Tezcatlipoca. Do you see the ressemblance?

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