Dugongs are marine animals which belong to the family Dugongidae. They are part of the order called Sirenia aka sea cows, which also includes the manatees. They can be found dispersed across the Indian ocean, Pacific ocean and the region between East Africa & Australia.
Here are five facts about them:
Apart from manatees, dugongs are the only marine animals that are strictly herbivorous, eating sea grass, weeds and aquatic plants. All other marine animals are omnivorous.
The closest relative of dugongs is the Steller’s Sea Cow, which was driven to extinction in the mid-1700s.
A dugong’s gestation period lasts one year and females give birth once every 3-7 years.
Although they resemble seals and walruses in appearance, dugongs are actually more genetically similar to elephants. That’s because these animals evolved from the same ancestor.
According to the IUCN Red List, dugongs have a “Vulnerable” classification; meaning they are very vulnerable to becoming extinct if conservation efforts aren’t set in place. As of today, less than 7500 dugongs are alive in the world.
The name “dugong” comes from the Malay word “duyung“, which means “Lady of the Sea“. Before scientists officially documented this species, sailors & fishermen out at sea assumed dugongs (and their cousins, the manatees) to be mermaids, sirens and other mystical creatures. This was predominantly because of the way these animals swam.
Dugongs and manatees rise out from the underneath the water and perform tail-stands (where they stand & balance on the tip of their tails) when coming up for air. This prompted sailors & fishermen to assume they were the mythical sea-dwelling creatures they grew up hearing about.
Sea Sponges are multi-cellular creatures that do not have a brain and organ systems and depend on the constant flow of water through their porous bodies to get the oxygen and food they need to survive. There are over 9000 recorded varieties of sea sponges in the world today and they can be found at various depths right from the seashore to the abyssal zone, which is the deepest part of the ocean.
Here are 5 fun facts about them:
Fossil records of sea sponges indicate that sponges first made an appearance on the Earth 650 million years ago. This makes them one of the earliest life forms on the planet.
There are currently 480,931 marine species known and on record and an estimated 2 million that are as yet unrecorded and unknown (i.e. there is not enough evidence – be it visual proof or physical proof – to classify any unknown animal as a distinct species) in all the lakes, seas and oceans of the world. It’s believed that 75% of the world’s entire marine population (480K + 2 Million) accounts for sponges.
Since they don’t have any age-rings (like in trees), it can be hard to accurately estimate the age of a sea sponge. But analysis of growth rates indicates that some sea sponges grow 0.2 mm (0.000656168 feet) per year. Based on this, sponges as small as 1 meter (3.2 feet) wide may be over 4500 years old!
A sea sponge in the Caribbean – Tectitethya crypta – produces two chemical compounds which can treat certain types of cancer and HIV. The chemicals – spongothymidine and spongouridine – have been used to develop the HIV drug Azidothymidine (AZT) which can be used to prevent mother-to-child and needle-to-skin AIDS/HIV transmission. The same chemicals have also helped create medication for leukemia and herpes.
The biggest debate since the time of Aristotle has been – “Are sea sponges plants or animals?” Although they resemble plants in appearance and remain permanently fixed to the spot they grow on like plants, sea sponges are not plants. Why?
– Sea sponges can’t produce their own food like plants and rely on stray organic matter to float into their pores via the flowing water.
– Sea sponges have an immune system like other animals which reject dissimilar cells if transplanted into them. Scientists need to use immunosuppressants to successfully transplant dissimilar cells into their bodies.
– Finally, some sea sponges produce and release sperm to indulge in sexual reproduction.
These characteristics makes sea sponges inherently animal-like.
Today, you can find a feminine hygiene product called “Menstrual Sponges” on the market. Basically, these are sea sponges that are used as re-usable tampons. In many parts of the world (especially in developed, first-world countries), sea sponges are a favoured alternative to toxic, non-biodegradable and expensive sanitary pads and tampons. Here is a link to theTop 5 most preferred sea sponge tampons.