Category Plants & Animals

What do sea pens do?

True to their names, sea pens resemble old-time quill writing pens. These colonial marine cnidarians (a large group of aquatic invertebrate animals) belong to the order Pennatulacea. Although the group is named for its supposed resemblance to antique quill pens, not all sea pen species live up to the comparison. Colours range from dark orange to yellow to white.

These underwater animals are actually a type of octocoral (soft coral), named for the eight stinging tentacles that they use to capture plankton (tiny floating plants and animals) to feed themselves. In fact, a single sea pen is both an individual and a colony. The basic unit of a sea pen, like all other corals, is a polyp, which consists of a sac-like body cavity enclosed by a mouth and surrounded by a ring of tentacles. The larva usually settles down in sand, mud, rubble or, sometimes, solid rock and this becomes the primary ployp. It buds into daughter polyps, and the sea pen grows. It is supported on a stem-like structure. While the larvae of some species settle close to their parents, others are carried great distances by ocean currents.

Some polyps feed by using nematocysts (a specialized cell in the tentacles of a jellyfish, corals and sea anemones, containing a barbed or venomous coiled thread that can be projected in self-defence or to capture prey) to catch plankton; some force polyps reproduce; and some force water in and out of canals that ventilate the colony.

Sea pens inhabit shallow and deep waters from the polar seas to the tropics. Some sea pens use a bulb inflated with water to anchor them to the sea floor. All have hard, internal skeletons, and at least some of them can glow in the dark.

Although many species live in shallow water, others have been found as deep as 20,013 feet (6,100 metres) below the surface. One species of Umbellula has been discovered living in cold, dark waters near Antarctica. It grows to about 10 feet (3 metres) long with a big, flat head of polyps at its end, the tentacles picking food out of the water as the head is pushed along by the current. Most sea pens, however, grow to between 2 inches and 6 feet, 7 inches (5 cm to 2 metres) in height.

 

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How birds are affected by habitat loss?

There are birds like the piping plovers (Charadrius melodus) that lay their eggs directly on the sand of a beach in a shallow depression. When sea-levels rise, beaches are washed away. When temperatures rise, and wetlands dry out, ducks that live and lay eggs on them will have nowhere to go.

Same is the fate of birds that depend on coral reefs. About one third of the carbon dioxide in the atmosphere is absorbed by the ocean. When CO2 increases and the weather gets warm, more CO2 is absorbed and water becomes more acidic. Increased acidity reduces the ability of the corals to secrete calcium carbonate, which forms the structure of the reef. As a result, they become brittle and break easily. The reef structures shrink (something that happened to the Great Barrier Reef). For many birds in the tropics, corals reefs provide an important food source and are critical habitats for survival.

In Hawaii, mosquitoes that carry malaria breed in lower attitudes. Mountaintops provide protection for birds from mosquitoes since they cannot reach the area. Increasing temperatures have led mosquitoes to move further up the mountain slopes, threatening the birds that live at the top of the mountain. Avian malaria is a major reason for the decline of Hawaiian birds.

When birds move out of their habitats in search of new places to occupy, they over-exploit prey sources, leading to destruction of the entire ecosystem. Ospreys have been seen hunting other birds, so they may pose a threat to birds in the area, particularly if fish become scarce.

Recently, peafowl were found across Kerala, surprising bird-watchers. Why did they move from their habitat? Obviously in search of food and shelter. Studies also show that some species of birds are developing shorter wing spans and have less density in their bones.

 

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What should we do to protect birds from climate change?

[1] Stop climate change. Even if we end releasing greenhouse gases now, there will be continued warming by the gases released earlier. Birds will have to face a warmer planet in the coming years.

[2] Preserve bird habitats. Restore them where they have been lost. Build artificial nesting sites (simple cages for sparrows to bring them back).

[3] Continues to observe and collect data on when birds arrive at certain spots, when their numbers decline, and the connection between their numbers and the year’s temperature patterns.

[4] Grow more trees. They help to balance climate changes, keep CO2 level low and give the birds a chance to nest and survive.

[5] Keep your cat indoors. Each year, outdoor cats kill more than a billion birds in the U.S. and Canada; keeping cats inside is safer for them and better for birds.

[6] Make the spaces around your house friendly for birds. Gardens, trees, and native flowers are good for people and birds.

[7] In a factory outside Chennai, migratory birds hit the glass windows often and crashed to the ground. The management built large nets under every window to save the birds.

[8] Wherever you find a place and time, talk about birds and the need to protect them. More than 30% of our breeding birds are already declining and are in need of conservation action.

 

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How do global warming and climate change affect birds?

A good example is the study of great tits (Parus major) in Europe. These birds reproduce when caterpillars come out in spring when the buds burst out. The caterpillars gorge on the new leaves, great tits pick up the caterpillars to feed the nestlings. This maintains the bird’s survival rates.

Bird reproduction takes place just when the caterpillars are in abundance before they form their cocoons. Warmer temperatures have led to caterpillars emerging sooner. The birds lay eggs too late, and the caterpillars are gone. The cues the birds use to reproduce are not matching up with the peak prey availability. This can reduce the number of eggs they lay.

Pied flycatchers (Ficedula hypoleuca) spend the winter in tropical Africa before migrating to Europe in the spring to breed, They use day-length change in their wintering grounds as a cue for migration. But prey availability is based on temperature, and due to climate change, it starts earlier in the year. The birds do not arrive at breeding grounds in time to take advantage of peak prey. See the mismatch? The fly-catcher population has declined more than 90% in some areas.

The snow bunting is adapted to very specific mountain habitats. When climate changes, they cannot find food. The ranges of boreal birds in Northern Europe are predicted to decrease by more than 73% over the next century.

 

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Who are the smallest subspecies of elephant in the world?

The Borneo elephant also known as the Borneo pygmy elephant (Elephas maximus borneensis) is unique to the forests of northeastern Borneo, Malaysia and Indonesia.

Rotund appearance

As its name implies, it is the smallest subspecies of the Asian elephant. Just under 8 foot tall, these elephants have large ears round belies, and long tails, so long that they could even brush the ground as they walk. The females are smaller than the males and either have tiny tusks or none at all. At the end of their long trunk is a single, prehensile finger, which it uses to collect grasses, leaves, fruits and other plants. Reaching down for a drink of water is easy too. One adult can eat up to 150 kg of vegetation per day. Favourite food? Of course, it’s durian and wild bananas which are common in its habitat.

Gentle nature

Borneo elephants are gentler compared to Asian and African elephants. In fact, there are very tame and quite passive, which has led some to believe that they once belonged to a domesticated herd. The story goes that in the 17th Century, the Sultan of Sulu was given a collection of captive elephants, and these were released into the jungles of Borneo. Scientific evidence by way of DNA studies shows that Borneo elephants are local to the region. Their lifespan is anywhere between 50 and 70 years.

Matriarchal system

Borneo elephants are sociable animals and live in matriarchal hierarchy. They form small groups of 8 individuals on average, which are dominated by females. Families typically comprise mothers, daughters, sisters and immature males (occasionally – an adult male). Mature males tend to be solitary or form temporary bull herd.

Behaviour

Family units occasionally gather together. This association is highly beneficial for them, helping keep genetic diversity, which, in turn, is vital for their survival. These active elephants are known to wander throughout their habitat, travelling up to 25-30 miles a day. Borneo elephants are migratory animals. Seasonal migration helps them keep themselves in good physical shape. They are good swimmers too.

Breeding

Calves are born after a gestation of 19-22 months. Only one calf is born. Elephants give birth about every 4-6 years, although this period may be extended when conditions are unfavourable for survival, such as during drought. The little one is fed by its mother till the age of three or four. It is the centre of attention among a herd.

Endangered

Pygmy elephants are an endangered species with barely around 1,500 individuals left in the wild, mostly found in Sabah in Malaysian Borneo. The primary threat to these elephants is habitat loss. As human encroachment wipes out forests, the herds are no longer able to travel along their traditional migration routes and sources of food. These homeless elephants also get killed in conflicts when they enter farmland and trample on crops are eat them up. Some get caught in snares erected by humans to trap other animals.

Hence, conserving forests and maintaining elephant corridors is essential if these elephants are to be saved from becoming extinct.

Quick facts

  • Borneo Pygmy elephants are native to Borneo Island.
  • They are smaller than African elephants.
  • They belong to Elephantidae family.
  • Their average life expectancy is in the range of 60-75 years.
  • They are cute and baby-faced.
  • The female can grow to a height of around 4 to 7 feet.
  • Males grow up to a height of around 7 to 8.2 feet.
  • They weight between 3000 – 5000kg.
  • They are usually grey, but occasionally the colour varies from brownish to blackish grey.

 

Picture Credit : Google

Can half of your brain be asleep?

Birds such as swifts, songbirds, seabirds, and sandpipers also sleep unihemispherically, with half of their brain shut. This helps them during long flights.

Keeping one half of the brain at rest, called unihemispheric slow-wave sleep, is in direct contrast to the typical situation where sleep and wakefulness are mutually exclusive states of the whole brain, the scientists say. “We have found that birds can detect approaching predators during unihemispheric slow-wave sleep, and that they can increase the use of unihemispheric sleep as the risk of predation increases,” they report.

The scientists studied groups of mallard ducks while they rested side by side and found that those at the edge of the group were significantly more likely to keep one eye open, with the closed eye being on the side of its nearest neighbour.

“We have found that birds sleeping under risky situations spend more time with one eye open and half the brain awake, and choose to direct the open eye towards a perceived threat,” added Dr Rattenborg.

 

Picture Credit : Google