Ocean Life Flashcards
What’s the main differences between Ediacaran and Cambrian ecosystems?
Ediacaran: two dimensional microbial mat surface, organisms are mostly ‘sessile’ and live on that flat surface, no burrowing or swimming
Cambrian: burrowing and mixing of layers, penetration of oxygen, some filter feeders, some swimmers, some predators, more three dimensional
How did ecosystems change in the Ordovician?
There was a shift from microbial environments to reef type environments.
Describe Ordovician reefs.
Dominated by sponges (porifera) which fed by ciliary action (choanocytes) and corals (sessile cnidarians) which form a mutualism with photosynthetic algae (zooxanthellae) e.g. Rugose corals and Tabulate
What animals inhabited Ordovician reefs?
-Crinoids (filter feeders)
-Cephalopods (swimming molluscs)
-Brachiopods (sessile feeders)
-Trilobites (3 part exoskeleton arthropods)
What are primary producers?
Organisms that produce their own energy (mainly via photosynthesis)
What caused an increase in diversity during the Ordovician?
Diversification of phytoplankton (the main primary producer) carried up the food chain allow more complex food chains/ webs to form.
What are zooplankton?
A diverse group of microorganisms that are primary consumers (heterotrophic)
List the main roles of a food chain/ web.
Primary producers, primary consumers, secondary consumers and apex predators.
What is the GOBE?
Great Ordovician Biodiversification Event
What is Sepkoski’s curve?
A graph which compiles fossil data over time showing animal diversification during the Palaeozoic. During the Ordovician the largest rise in animal variety occurred.
What caused the GOBE?
- Splitting of the continents lead to large volcanic activity, combined with global warming this lead to high sea levels and larger oceanic shelf (shallow seas=good for evolution)
- Strontium excursion could have increased nutrient levels.
Describe the end Ordovician extinction event.
The first of the big five extinction events in Earth’s history. It was comprised of two pulses. The first was due to global cooling (glaciation and sea level drop) and the second was due to changing ocean cycles leading to anoxia.
What are vertebrates?
Vertebrates are part of the phylum Chordata, and they can be divided into jawless vertebrates (agnathans) and jawed vertebrates (gnathostomes).
List the characteristics of vertebrates.
-All chordate characteristics e.g. notochord, pharyngeal slits…
-Segmented brain
-Medial fins
-Branchial arches (important)
-Paired eyes
What characteristics do agnathans have?
They are jawless, have keratin teeth and no appendages e.g. Lamprey/ Hagfish
What characteristics do gnathostomes have?
They are jawed, have teeth, mineralised bone, paired appendages.
List the sequence of events/ phases that happens during the development of an animal.
Zygote, cleavage, blastula (ball of cells), gastrula (folds to form a gut cavity), endo and ectoderm formation, larva and adult.
What are Homeobox (Hox) genes?
Genes that code for what is expressed in different parts of the body. For example brachial arches develop into different things depending on the Hox genes present.
What two jawless vertebrates are stem group relatives to modern vertebrates?
Metaspriggina and Sacabambaspis
What were ostracoderms?
Armoured jawless fish which were diverse and dominant during the Silurian. e.g. Sacabambaspis and Cephalaspis
What are placoderms?
Armoured and jawed animals that also dominated the Silurian e.g. Dunkleosteus
What was the Devonian Nekton revolution?
The rapid occupation of the deep water column leading to advancement in predatorial ecological complexity.
What caused the ostracoderms to go extinct during the Devonian?
The collision of the North American and Europe to Euramerica reduced the abundance of shallow waters which ostracoderms relied on. Fossils evidence also suggests large predation by jawed competitors.
