To say that sponges are old is the understatement of the era. They made their entrance on to earth about 600-800 million years ago. Talk about arriving to the party early. One particularly keen party sponge is so mysterious, it does not appear to have a common name. It is only known as Monorhaphis chuni. This deep sea sponge is unique in that it forms a spicule pillar that can reach up to 3m long! It uses this to anchor itself to the sediments below.
So how long-lived is this wise old sponge of the deep? Well, as amazing as sponges are, they cannot communicate their age without being dissected. A standard sponge aging method involves counting the dark and light rings in the sponges’ skeleton (much like aging a tree). Another way is to estimate the amount of the isotope Silicon-32 decaying within the siliceous sponges’ spicules (try saying that in a hurry!). However, these methods would not work on this spongey customer.
Fortunately, a group of scientists (Peter-Jochum et al., 2012) came up with the clever method of working out the sea temperature at the beginning of its life span. To do this, they studied an extraordinarily large spicule that was discovered 1100m deep in the East China Sea. Using the oxygen isotopic composition and Mg/Ca ratios of the spicule, they estimated that the sea temperature was 1.9 degrees when this sponge was…well…a young sponge. By comparing that to the relatively tropical temperature of 4 degrees nowadays, the scientists predicted that the spicule had been around for 11, 000 years!!.. Well give or take 3000 years, but hey, cut those hard-working nerds some slack!
Not only does this make this sponge one of the longest living animal species still in existence, its skeleton tells a tale that makes lord of the rings look like a comic book. It weaves a story of previously unknown climate change such as deep sea temperature fluctuations over millions of years. Think that the sponge information out there is saturated? This gives reason to believe that there is so much more to learn from sponges!