GODT NYTT ÅR

JELLYFISH: GAGISAMA

These festive lovelies are jellyfish. Jellyfish are found all over the world, from surface waters to our deepest seas — and they are old. They are some of the oldest animals in the fossil record.

Sea jellies and jellyfish are the common names for the medusa-phase or adult phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria — more closely related to anemones and corals.

Jellyfish are not fish at all. Jellyfish evolved millions of years before true fish. 

The oldest conulariid scyphozoans — picture an ice-cream cone with fourfold symmetry — appeared between 635 and 577 million years ago in the Neoproterozoic of the Lantian Formation a 150-meter-thick sequence of rocks deposited in southern China. 

Others are found in the youngest Ediacaran rocks of the Tamengo Formation of Brazil, c. 505 mya, through to the Triassic. Cubozoans and hydrozoans appeared in the Cambrian of the Marjum Formation in Utah, USA, c. 540 mya. Like other soft-bodied organisms, ctenophores (comb jellies), sea jellies and jellyfish only produce fossils only under exceptional taphonomic conditions — think rare.

I have seen all sorts of their brethren growing up on the west coast of Canada. I have seen them in tide pools, washed up on the beach and swam amongst thousands of Moon Jellyfish while scuba diving in the Salish Sea. Their movement in the water is marvellous.  

In the Kwak̓wala language of the Kwakiutl or Kwakwaka'wakw, speakers of Kwak'wala, of the Pacific Northwest, jellyfish are known as ǥaǥisama.

The watercolour ǥaǥisama you see here is a bit of fancy. While I chose blue, purple and pink for these lovelies, they also come in bright yellow, orange and relatively clear — and are often luminescent.

Jellyfish such as comb jellies produce bright flashes to startle a predator, others such as siphonophores can produce a chain of light or release thousands of glowing particles into the water as a mimic of small plankton to confuse the predator.

For most jellyfish bioluminescence is used for defence against predators — and about half of all jellyfish are bioluminescent. Some produce a glowing sticky slime that clings to predators making them vulnerable to other predators. Some jellyfish can release their tentacles as glowing decoys. So you see that there are many strategies for using bioluminescence by jellyfish.

All bioluminescence comes from energy released from a chemical reaction. This is very different from other sources of light, such as from the sun or a light bulb, where the energy comes from heat. In a luminescent reaction, two types of chemicals, called luciferin and luciferase, combine together. The luciferase acts as an enzyme, allowing the luciferin to release energy as it is oxidized. The colour of the light depends on the chemical structures of the chemicals. 

There are more than a dozen known chemical luminescent systems, indicating that bioluminescence evolved independently in different groups of organisms. One type of luciferin is called coelenterazine, found in jellyfish, shrimp, and fish. Dinoflagellates and krill share another class of unique luciferins, while ostracods (firefleas) and some fish have a completely different luciferin. The occurrence of identical luciferins for different types of organisms suggests a dietary source for some groups. Organisms such as bacteria and fireflies have unique luminescent chemistries. In many other groups, the chemistry is still unknown

Some of the most amazing deep-sea jellyfish are the comb jellies, which can get as large as a basketball, and are in some cases so fragile that they are almost impossible to collect intact.

Also spectacular are the siphonophores, some of which can reach several meters in length. Siphonophores deploy many tentacles like a gill net casting for small fish.

ORYGMASPIS OF THE TANGLEFOOT

This calcified beauty is Orygmaspis (Parabolinoides) spinula (Westrop, 1986) an Upper Cambrian trilobite from the McKay Group near Tanglefoot Mountain in the Kootenay Rockies. 

Orygmaspis is a genus of asaphid trilobite with an inverted egg-shaped outline, a wide headshield, small eyes, long genal spines, 12 spined thorax segments and a small, short tail shield, with four pairs of spines. 

Asaphida is comprised of six superfamilies found as marine fossils that date from the Middle Cambrian through to the Ordovician — Anomocaroidea, Asaphoidea, Cyclopygoidea, Dikelocephaloidea, Remopleuridoidea and Trinucleioidea. It was here, in the Ordovician, that five of the six lineages met their end along with 60% of all marine life at the time. They did leave us with some wonderful examples of their form and adaptations. The stubby eyed Asaphids evolved to give us Asaphus kowalewskii with delightfully long eyestalks. These specialized protrusions would have given that lovely species a much better field of view in which to hunt Ordovician seas — and avoid becoming the hunted.

Only the hardy Superfamily Trinucleiodea pushed through. They were to meet their end in the final days of the Silurian where yet another cataclysmic event wiped out much of the life on Earth, including the last remains of Asaphida (Fortey & Chatterton, 1988).

The outline of the exoskeleton Orygmaspis is inverted egg-shaped, with a parabolic headshield — or cephalon less than twice as wide as long. Picture a 2-D egg where the head is wider than the tail.

The glabella, the well-defined central raised area excluding the backward occipital ring, is ¾× as wide as long, moderately convex, truncate-tapering, with 3 pairs of shallow to obsolete lateral furrows. 

The occipital ring is well defined. The distance between the glabella and the border (or preglabellar field) is ±¼× as long as the glabella. This fellow had small to medium-sized eyes, 12-20% of the length of the cephalon. These were positioned between the front and the middle of the glabella and about ⅓ as far out as the glabella is wide. 

The remaining parts of the cephalon, the fixed and free cheeks — or fixigenae and librigenae — are relatively flat. The fracture lines or sutures — that separate the librigenae from the fixigenae in moulting — are divergent just in front of the eyes. These become parallel near the border furrow and strongly convergent at the margin. 

From the back of the eyes, the sutures bend out, then in, diverging outward and backward at approximately 45°, cutting the posterior margin well within the inner bend of the spine — or opisthoparian sutures. 

The thorax or articulating middle part of the body has 12 segments. The anteriormost segment gradually narrows into a sideward directed point, while further to the back the spines are directed outward and the spine is of increasing length up until the ninth spine, while the spine on the tenth segment is abruptly smaller, and 11 and 12 even more so. 

This fellow has a wee pygidium or tail shield that is only about ⅓× as wide as the cephalon. It is narrowly transverse about 2× wider than long. Its axis is slightly wider than the pleural fields to each side, and has up to 4 axial rings and a terminal and almost reaches the margin. Up to 4 pleural segments with obsolete interpleural grooves and shallow pleural furrows. The posterior margin has 3 or 4 pairs of spines, getting smaller further to the back. 

References:

Chatterton, Brian D. E.; Gibb, Stacey (2016). Furongian (Upper Cambrian) Trilobites from the McKay Group, Bull River Valley, Near Cranbrook, Southeastern British Columbia, Canada; Issue 35 of Palaeontographica Canadiana; ISBN: 978-1-897095-79-9

Moore, R.C. (1959). Arthropoda I - Arthropoda General Features, Proarthropoda, Euarthropoda General Features, Trilobitomorpha. Treatise on Invertebrate Paleontology. Part O. Boulder, Colorado/Lawrence, Kansas: Geological Society of America/University of Kansas Press. pp. O272–O273. ISBN 0-8137-3015-5.

KOURISODON PUNTLEDGENSIS

Kourisodon puntledgensis

Mosasaurs were large, globally distributed marine predators who dominated our Late Cretaceous oceans. Since the unearthing of the first mosasaur in 1766 (Mulder, 2003) we've discovered their fossil remains most everywhere around the globe — New Zealand, Antarctica, Africa, North and South America, Europe and Japan.

We've now found the fossil remains of an elasmosaur and two mosasaurs along the banks of the Puntledge River, says Dan Bowen, Chair of the Vancouver Island Palaeontological Society.

The first set of about 10 mosasaurs vertebrae (Platecarpus) was found by Tim O’Bear and unearthed by a team of VIPS and Museum enthusiasts led by Dr. Rolf Ludvigsen. Dan Bowen and Joe Morin of the VIPS prepped these specimens for the Museum.

In 1993, a new species of mosasaur, Kourisodon puntledgensis, a razor-toothed mosasaur, was found upstream from the elasmosaur site by Joe Zembiliwich on a fossil field trip led by Mike Trask. 

A replica of this specimen now calls The Canadian Fossil Discovery Centre in Morden home. What is significant about this specimen is that it is a new genus and species. At 4.5 meters, it is a bit smaller than most mosasaurs and similar to Clidastes, but just as mighty. It shared its environment with a variety of Elasmosaurids, turtles, and other mosasaurs, although it seems that no polycotylids were present in its Pacific environment.

Interestingly, this species has been found in this one locality in Canada and across the Pacific in the basal part of the Upper Cretaceous — middle Campanian to Maastrichtian — of the Izumi Group, Izumi Mountains and Awaji Island of southwestern Japan. We see an interesting correlation with the ammonite fauna from these two regions as well. What we do not see is a correlation between our Pacific fauna and those from our neighbouring province to the east. Betsy Nicholls and Dirk Meckert published on the marine reptiles from the Nanaimo Group (Upper Cretaceous) of Vancouver Island in the Canadian Journal of Earth Sciences in 2002. What we see in our faunal mix reinforces the provinciality of the Pacific faunas and their isolation from contemporaneous faunas in the Western Interior Seaway.