Seastar and Algae
Life in our world’s oceans constitute a significant portion of all biomass on Earth—over 90% of all biomass is found in these marine environments. It is estimated that there are 2.2 million species living in the oceans, while over two-thirds remain unknown. One of the major drivers of biodiversity in marine ecosystems is plankton. Plankton are at the base of all marine ecosystem food webs, and they provide up to 85% of the world’s oxygen—dependent on the yearly variation. Without plankton, our oceans would not thrive with life and climate would be greatly affected. Therefore, it is essential that we communicate their importance in marine systems given the impacts of climate change and ocean acidification on marine systems today.
Trav Tai, MSc
Crustacean – Crab and Barnacles
Phanerozioc Eon – Proterozoic Era: Cambrian Period
The Cambrian Explosion Period (541-485.4 million years ago) marked the accelerated diversification of species: molluscs (Mollusca) and arthropods: the remarkable beginning of modern groups of species evolving in the oceans while the land was constrastly barren.
What brought this sudden shift of event? It was during the Proterozoic Era or PreCambian Time that saw rising levels of oxygen in the atmosphere including an ozone layer to block out harmful ultraviolet radiations from the Sun, thus making complex life feasible. This influx of oxygen in the atmosphere could be attributed from the emissions of photosynthesizing cyanobacteria and algae in force. In addition, at the advent of the Cambrian Period, the massive supercontinent Rodinia (Proterozoic Era) was drifting into fragmented continents, pushing sea levels up to the edges of the continents. Thus, the rising sea levels flooded the low-lying landmasses to create shallow, marine habitats ideal for spawning new life-forms. The environment was warmer and friendly for early diverse arthropods and mollusc species to multiply everywhere.
What are Molluscs? Molluscs or mollusks, the second largest phylum of animals estimated 100,000 species, are a group of invertebrates that include organisms like squids, clams, scallops, oysters, abalone, snails and chitons. The majority of mollusks are found in the oceans from the seashore to the deep abyssal zone. Mollusks have a good impact on our ecosystems. For example, the water snail besides being a source of food for fish including trout and salmon, are also recycles of plant and animals waste, essentially keeping water clean and healthy.
The Earth’s evolution and extinction processes are phenomenal. Arthropod fossils were discovered from early Cambrian period to Jurrasic period in places like Canada, United Kingdom, United States, China and others. Arthropods are the ancestors of insects, arachnids and crustaceans. Arthropods account for 80% of all known living animal species.
Crustaceans form a very big group of arthropods and are mainly aquatic animals including crabs, lobsters, krills, prawns, shrimps, crayfish. Other types of crustaceans are terrestrial (woodlice), parasitic (fish lice, tongue worms) and sessile (barnacles) and arachnids. Barnacles are covered with calcium carbonate and live on hard surfaces like rocks. Arachnids are 8-legged creatures like spiders, scorpions.
Conservation of the marine species is critical. It is staggering that over 10 million tons of crustaceans are caught for human consumptions today. Krills and biopods, a vital part of the marine food chain, could be the greatest biomass animals on Earth. Hopefully, humans will not resort to krills and bipods as the next target when other crustaceans are depleted from overfishing or others.
At the end of the Cambrian Period, there was a massive extinction of many species. The cause of this mass extinction is unclear, however, it could be due to climatic changes effecting polar oceans temperatures and oxygen content. Fossil records indicate that many species were extinct except numbers of different species of trilobites (first arthropods), archaeocyathis (reef-building sponges), and brachiopods (shellfish) survived although they were severely depleted.
Geologica – Earth’s Dynamic Forces, Dr. Robert R. Coenraads and John I. Koivula (2007). Fossil site: Burgess Shale, Yoho National Park, British Columbia and Rocky Mountains, Canada www.pc.gc.ca
Sea Surface Temperatures at Highest in 150 Years: Species Shift with Climate Change (scienceworldreport.com)