Marine Creature of the Month Sept '20

 Marine Creature of the Month

Famous Fish: Spongebob Squarepants

For our last Famous Fish we are going out in style. You voted for everyone's favourite yellow sponge, the man himself: Spongebob Squarepants. Come with me to Bikini Bottom as we learn all about him!

Kingdom: Animalia
Class: Calcarea, Hexactinellida, Demospongiae, Homoscleromorpha, Stromatoporoidea
Conservation Status: Not assessed

WHAT IS SPONGEBOB?

He is a sea sponge. Not surprising really, his name is Spongebob after all. What is surprising is that natural sea sponges look less like the things you use to clean the dishes and more like something you'd find on an alien planet! They come in all shapes and sizes. While they look more like plants they are definitely classed as animals. In fact, they were the first species to branch off from the common ancestor to all animals. They may lack true tissues and organs, but they function enough like an animal to be classified as one. Such as, they produce sperm cells and lack cell walls. For anyone who vaguely remembers school biology, cell walls are a defining feature of plant life.

There are over 10,000 known species of sea sponge. 10,000! I am going to be talking about sponges in general today but will offer a nice variety of pictures!

HOW DOES SPONGEBOB FUNCTION?

Do you remember the episode where Spongebob becomes agoraphobic? He stays inside with three bits of rubbish and begins to filter feed? Well, that is a more accurate depiction than him being a burger flipping, jellyfishing goofy goober.

Sponges live fixed to their location and are designed to efficiently filter the water for food and nutrients. Water flows in through their central cavity where nutrients are deposited before it exits through the osculum - a small hole. Being a creature which lives in a fixed location makes sponges a sessile species. They attach themselves to a marine surface, usually corals or rocks, and stay there for the rest of their lives. Some species live deeper than 8,800m (5.5 miles) below the surface!

Most species of sponge filter feed but there are a rare few which prey on small crustaceans. This is due to living in food poor environments. At the opposite end of the scale, some sponges form a symbiotic relationship with photosynthesising microorganisms. These produce more food than they know what do with in some cases!

The system which they use for filter feeding, the flow of water through their central cavity, is also used for respiration and waste excretion.

WHAT IS SPONGEBOB'S LIFECYCLE?

It would seem on the show, Spongebob is aged anywhere between 17 and 35. You can see his date of birth on his driver's license, but like all good children's protagonist he functions as a wide range of ages. Keeps him relatable to all ages.

In real life, most species only live for a few years. Some tropical species of sponges out live their cousins' feeble life expectancy and can live up to 200 years. Possibly even longer! Considering how long Spongebob has been on the air, my guess is he is a tropical sponge! Reaching maturity depends on the species of sponge and how long they live. Those with shorter life expectancies reach maturity after just a couple weeks, while some take years to reach it.

Being such a varied species, there are many ways which sponges can reproduce. There are three asexual methods that are known and then your standard sexual reproduction. Most sponges are hermaphrodites, meaning they are both sexes simultaneously. They all have the capacity to produce sperm, either as something to expel or to withdraw inside itself. The withdrawn sperm becomes like a cyst and then eventually an egg. And the rest? Well, one spawns and the other receives. From there, they produce eggs which are usually retained until hatched. Of course, with there being such a vast number of species there are some which release the fertilised eggs into the water.

Once hatched, the larvae will float and swim for a few days until sinking. Here they find more permanent residence and grow to their heart's content.

With asexual reproduction, sponges can reproduce by fragmenting, budding, or producing gemmules. Parts of sponges may break off, or fragment if you will, in the ocean's currents. These parts are transported and find new suitable habitats, where they regrow but only if they have the right cells present. Fragmented sponges need both collenytes present to be able to produce the cells necessary fro regrowth.

Gemmules are internal pods found within certain species of sponge. These contain a mass of cells which will spawn new life. They tend to be released when dying, although some species do it seasonally. Sometimes they are not released and the gemmules will spawn inside the parent sponge, making it difficult to determine if the original sponge has regenerated or been colonised! As for budding, very few species reproduce this way. This is when a new organism is spawned from a growth, or bud, on the original.

 

DOES ANYTHING THREATEN SPONGEBOB?

Plankton, on a daily basis. And he went to college so you know he knows what he's on about.

In all seriousness, much like everything in our oceans, sponges are threatened by the ever changing climate and acidic levels of the sea. However, it is not actively being measured or assessed, despite just how useful sponges are to the ecosystem. They are detritivores, meaning they eat the detritus. Aka, dead stuff. The detritus would build up and clog the ecosystem if it weren't for the critters which eat it. Sponges clean up the ocean as much as they clean your dishes!

Over the years, humanity has found many used for sea sponges. From helmet padding to filtering water, sea sponges were used for pretty much everything we use synthetic sponges for today. In fact, the invention of the synthetic sponge saw a decrease in use of sea sponge - so they certainly have that going for them. If only they had been made from a more sustainable substance... Prior to this, though, their extensive usage nearly brought the hipposongia and spongia species to extinction. Classic case of humans taking too much and not having the forethought to think of the impact it will have.

FUN FACTS

• Although most species of sponge do not move, there are a few which can move up to 4mm per day by contracting their bodies! Some even use the amoeba-like movement of their cells.
• A sponge's age can be estimated by its growth rate and size. There are some sponges which grow 0.2mm a year which measure over 1m - putting their age somewhere near the 5,000 mark!
• There are four types of larvae which sponges will hatch into.
• As they have very little to defend themselves with, some sponges have evolved to take on materials which make them less appealing to predators.
• Dolphins have been observed using sponges to protect their noses while hunting on the sea floor. The technique seems to be fairly recent and passed down from mother to daughter.
• There are two species of sponge which have a symbiotic relationship. One lives on higher rocky surfaces while they other does not taste nice to star fish. Guess what eats the former. The two sponges have grown into each other to offer higher living and protection from sea stars.
• Spongebob is voiced by Tom Kenny. Those of you with keen ears will have heard in him Adventure Time, Powerpuff Girls, and many more animated shows!
• Stephen Hillenburg, creator of Spongebob Squarepants, was educated in marine biology.
• Spongebob's parents look a little more like sea sponges that the sponge himself does. This was intentional, as it was a more recognisable shape and easier to anthropomorphise a dish sponge.
• There have been numerous guest stars on the show, including Johnny Depp, Victoria Beckham, Scarlett Johansson, and Jonathan Rhys-Davis. The second film even starred Antonio Banderas!
• Spongebob is the only show still running new episodes on Nickelodeon which originally aired in the 90s. Sure, it started in 1999 but it still counts!
  

 

What has been your favourite thing to learn about Spongebob? Do you know any fun facts about sea sponges? What would you like to learn about next? Lemme know, below!

One last thing. Want to see how a sponge "breathes", then check out this video.

Listening to: This is The Rasmus