What Makes Sponges Different Than Other Animals

Abstract

Sponges are animals that live in oceans, lakes, and rivers. There are close to 10,000 sponge species described by scientists, just far more species await discovery! However, not all sponges look and feel like their kitchen-sink cousins. Over fourth dimension, sponges have evolved into many sizes and shapes, giving u.s.a. the huge diversity of sponge species on Earth today. For example, many sponges are rock-hard! These rock sponges apply minerals like silica (glass) to build their skeletons—instead of os like ours. Other sponges have evolved unique means to eat. Most sponges filter water to get their food, but certain sponges are carnivorous, pregnant that they eat meat, including tiny shrimp-similar creatures. Sponge species with different body and skeleton shapes and sizes tin thrive in very different and unique environments.

What Is a Sponge?

Have you ever looked closely at a living sponge? Although they may look more than like plants or fungi, sponges are actually animals. Sponges live in waters all effectually the world, from the deep seas of the Arctic and Antarctic to the shallow and warm tropical seas, likewise every bit in rivers, streams, ponds, and lakes [one]. Adult sponges do non move around—they are fixed to the bottom of the seafloor, on rocks, or on other sandy or hard underwater surfaces (Effigy 1).

• Figure 1 - (A–F) Examples of various-shaped sponges and their common names.
• (G) The Venus' flower basket sponge provides a home for tiny shrimps. (H) Spicules are microscopic structures, made of silica (drinking glass) or calcium carbonate (similar to limestone), that make up a sponge's body. Find the many unique shapes of the spicules.

Different humans, sponges exercise non have stomachs, organs, backbones, or claret. Still, they are multicellular animals, which ways that they are made upwards of many cells that piece of work together, similar in the human being body. If you put a sponge in a blender, the cells can recognize each other later and reform into tiny sponges! Sponges are the simply animals that can rebuild themselves if they are torn apart!

Sponges have many different sizes and shapes. They can be huge and round, or make thin crusts on rocks, or even look similar vases or cups (Figures 1A–F). Larger sponges tin can also serve every bit homes for other animals like fishes, turtles, and shrimps (Figure 1G).

The sponge body is fabricated of holes and channels through which water is pumped and filtered to obtain particles of food. Because they filter the water, sponges are called filter feeders [2]. Some sponges can filter upwards to 50,000 times their own volume in a day. This would be like an average-sized person drinking 3,500 50 (or 925 gallons) of water in a 24-hour interval! Due to this water flow through their bodies, sponges are very important in marine ecosystems.

How exercise sponges filter and so much water? Within their tissue, they take chambers that are lined with special cells that have tail-like appendages called flagella. These tails all wiggle effectually together to create a h2o current through the sponge body. This current makes the water menstruation through the sponge and provides the sponge with food and oxygen. This explains why most sponges are full of tubes and holes: they allow the water to flow around inside the sponge [ii].

What Makes a Sponge Spongy or Rock-Similar?

Some sponge species accept lots of tiny, hard parts chosen spicules that assemble into a skeleton and brand their bodies stiff. Spicules are made of either calcium carbonate (similar to limestone) or silicon dioxide (quartz/glass), and they come up in a boundless variety of shapes and sizes (Figure 1H). A single sponge can comprise several different types of spicules [2]. Spicules are what make some species "spongy" and others "rock-like." Sponges without spicules are by and large the virtually squishy and spongy, like our bath sponge (Figure 1F). Although well-nigh mod kitchen and bath sponges are made of plastic, sponges without spicules, like the Mediterranean bath sponge Spongia officinalis, have been used by humans for thousands of years every bit cleaning tools, among other uses. These are the species that kitchen sponges effort to mimic. Other sponges have evolved dense skeletons packed with hard spicules. Some of these spicules can form an interlocked network that makes the sponge hard as a rock, and they are unsurprisingly known every bit rock sponges (Figure 1D) [three]. These spicules are very strong, only they tin still be aptitude, and light can pass through them. This combination of properties makes spicules very interesting to both materials scientists and biologists.

Sponges can look very similar when we hold them in our easily, so scientists called taxonomists need to wait closely for unique characteristics to tell species autonomously from one another. Spicules play a very important role in this process because they are unique and tin exist used to identify different species. Spicules can fifty-fifty be used to identify totally new species of sponges. There are over nine,350 known sponge species in the world. Each of these species has either a distinctive gear up of spicules or, if the sponge is soft, no spicules at all [iii].

The Curious Case of Cannibal Sponges

In addition to making some sponge species rock-like, development has also driven other changes in sponges over many millions of years. Although most sponges are filter feeders, certain species have adult techniques to swallow larger prey, such as larvae and crabs (Effigy 2). These are called carnivorous sponges, meaning that they eat meat. Carnivorous sponges accept lost the ability to filter food from the water.

• Figure 2 - A series of images taken over time, showing a small cannibal sponge (1–3 cm in length) in an aquarium.
• The sponge catches two tiny shrimps with its claw-like spicules. Although the "arms" are large plenty to be seen with the naked eye, the spicules that line the arms are so small that they can only be seen under a microscope (Epitome credit: J. Vacelet).

Most cannibal sponges live in the abyssal at depths of more 4,000 one thousand (13,123 anxiety). In some regions, these sponges are the most common animals, surviving the cold, dark, crushing pressures of the deep sea. Scientists call back that eating meat is a tactic certain sponges employ to survive when other ways of finding food do not work. A similar strategy is used by some plants, similar the Venus fly trap, which evolved carnivory to live in food-poor habitats.

Carnivorous sponges by and large accept long fishing-rod-like "arms" lined with hook-like spicules that are used to capture casualty. The spicules piece of work similar hook-and-loop fasteners, like Velcro or the seeds that get stuck to you when you walk outside. Casualty animals caught in these hooks are slowly digested by the sponge. Sponges catch their nutrient slowly, and it can take them several days to digest their catch.

It is not clear when this unique feeding mechanism evolved, only scientists think that cannibal sponges take been on Earth for at least 60 million years, significant that they appeared just later the dinosaur age ended. Since then, at to the lowest degree 150 sponge species take evolved to exist carnivorous to survive in extreme, nutrient-poor environments such as the deep ocean [4].

Sponges Accept Been on World for More than Than 550 Million Years!

It is likely that sponges were the first animals that evolved on Earth. However, not all sponge groups accept survived since then. Some species went extinct, while others adjusted (similar the carnivorous sponges) to survive harsh climatic conditions such as decreased oxygen in the h2o and increased temperatures acquired by global warming. To appointment, Earth has experienced 5 big extinction events, and one of the biggest occurred 250 meg years ago, before the dinosaurs even existed. This extinction is known as The Great Dying. During The Groovy Dying, 90% of all ocean life went extinct. It was a harsh fourth dimension for sponges, and only a handful of species survived. One of the surviving groups was the rock sponges.

Paleontologists that work with fossils know that rock sponges made it through The Keen Dying because scientists have found the skeletal remains of these sponges from the Cambrian Period (most 550 1000000 years agone) onwards throughout the Globe'due south history. In the fossil record, the skeletons of rock sponges remain largely whole and can be used to place rock sponges fifty-fifty after millions of years (Figure iii). This is very unique amongst sponges. Most other "spongier" sponges that have only a few loose spicules or no spicules at all are less preserved in the fossil record considering they do non have a formed skeleton. This ways that fifty-fifty if paleontologists do find the spicules of these softer sponges, it is much more difficult to identify the species—a bit like finding just a little finger bone instead of a whole skeleton [5].

• Figure 3 - (A) Example of a fossil exploration site near Albufeira in the S of Portugal, where loose rock sponge spicules were establish within white rocks.
• (B) Bodies of preserved fossil sponges of diverse shapes and ages. (C) A well-nigh whole fossil rock sponge skeleton, after handling with acid to remove the stony part around the skeleton.

Conclusions

The species of sponges that we humans use and are most familiar with are just a few examples of the numerous diverse groups of sponges that exist in nature. Sponges have adapted to lots of different habitats and environmental changes over hundreds of millions of years. These adaptations helped them outlast not simply the dinosaurs, simply also many other plant and animal species.

Although sponges have various body shapes, colors, and spicule shapes, they still are some of the simplest animals that exist. Nevertheless, from the fossil record, we know that sponges were quite abundant in the by and they are still plentiful today. Like many other animals, sponges are affected by man activities. This means that sponges can be harmed by climate alter, pollution, and over-fishing. As nosotros accept steps to protect our oceans from these homo-fabricated threats, nosotros should be certain to remember the sponges and include these ancient and fascinating animals in our conservation plans.

Funding

We give thanks the Villum Fonden Grant No. 16518. Part of this piece of work was made possible by the European Society for Evolutionary Biological science (ESEB) outreach fund granted to Equally.

Glossary

Filter Feeders: ↑ Are animals that feet on food particles from the water. Examples are sponges, baleen whales and sharks.

Flagella: ↑ Wildly whipping tail structures keeping the water moving inside the sponge torso.

Spicules: ↑ A tiny structure made up of minerals that serves as a piece of the skeleton of sponges and other marine or freshwater animals.

Taxonomists: ↑ A scientist who groups organisms into categories and studies the relationships betwixt various types of organisms.

Carnivorous: ↑ If an animal feeds on other animals tissues, meaning eating its meat, it is chosen a carnivorous fauna.

Paleontologists: ↑ A scientist who studies fossils and the history of life on Earth.

Fossil Record: ↑ Remains of animals and plants that lived in the past (fossils) and their placement in the rock germination (record).

Conflict of Involvement

The authors declare that the research was conducted in the absenteeism of any commercial or financial relationships that could be construed as a potential conflict of interest.

Acknowledgments

Nosotros thank Samuel Rarau (12 years) for giving us helpful feedback on our figures. We thank Shirley Pomponi from the Harbor Co-operative Oceanographic Establish (HBOI, Florida, USA) for providing the underwater sponge pictures of the stone sponge in Figure 1, Lisa Eckford-Soper from the University of Southern Kingdom of denmark for the bath sponge flick, Andrzej Pisera from the Polish University of Sciences (Warsaw, Poland) for the picture in Figure 3C and Prof. Dr. Jean Vacelet from the Marine Station of Endoume, Marseille, French republic for the carnivorous sponge pictures in Figure 2. We want to thank our young reviewer Juniper for her first-class feedback to our article.

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References

[1] ↑ Van Soest, R. W. One thousand., Boury-Esnault, N., Vacelet, J., Dohrmann, M., Erpenbeck, D., De Voogd, N. J., et al. 2011. Global diversity of sponges (Porifera). PLoS ONE. 7:e35105. doi: 10.1371/journal.pone.0035105

[2] ↑ Bergquist, P. R. 1978. Sponges. London: University of California Press, Berkeley & Los Angeles; Hutchinson.

[3] ↑ Schuster, A., Erpenbeck, D., Pisera, A., Hooper, J., Bryce, M., Fromont J, et al. 2015. Deceptive desmas: molecular phylogenetics suggests a new nomenclature and uncovers convergent evolution of lithistid demosponges. PLoS 1. 10:e116038. doi: 10.1371/journal.pone.0116038

[four] ↑ Vacelet, J., and Bourny-Esnault, N. 1995 Carnivorous sponges. Nature. 373:333–five. doi: 10.1038/373333a0

[v] ↑ Pisera, A. 2006. Palaeontology of sponges-a review. Can. J. Zool. 84:242–61. doi: x.1139/z05-169

Source: https://kids.frontiersin.org/articles/10.3389/frym.2022.682878

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