What does Notothenioid have in common?
These include the presence of three flat pectoral fin radials, nostrils located laterally on each side of the head, the lack of a swim bladder, and the presence of multiple lateral lines. Because notothenioids lack a swim bladder, the majority of species are benthic or demersal in nature.
What do Notothenioid fish eat?
These fish have no swim bladder, an internal gas filled organ that helps fish to maintain buoyancy. Hence, they are demersal (living near the bottom of the sea). Icefish feed on fish and krill. They have very large heads, spoon shaped lower jaws and large toothy mouths.
How did notothenioids get the gene for antifreeze proteins?
How did notothenioids “get” the gene for antifreeze proteins? The gene arose from random mutations. Students may include additional details from the film, such as the fact that another gene was duplicated and several mutations occurred in the duplication.
Why do icefish have no hemoglobin?
So, as other species of fish died off in Antarctic waters, notothenioids thrived and diversified. In addition to having antifreeze proteins, icefish do not produce red blood cells or hemoglobin. As a result, their blood is less viscous and can flow easily even at very cold temperatures.
How did icefish get the antifreeze gene?
How did icefish eliminate hemoglobin?
Icefish compensate for their lack of hemoglobin with a variety of other adaptations, including a large heart, wide blood vessels, large gills, and no scales. These adaptations increase their blood flow and the amount of oxygen that diffuses into their blood.
What is the antifreeze protein called?
AFPs
Antifreeze proteins (AFPs) are biological antifreeze materials originally found in polar fish; AFPs can bind to ice and subsequently inhibit the growth of the ice crystals.
What is unusual about icefish blood?
The icefish of the Channichthyidae family are unusual in several ways — they lack scales and have transparent bones, for example — but what stands out most is their so-called white blood, which is unique among vertebrates.
What geographical event led to the evolution of icefish?
Antarctica went through a major period of cooling around 24 million years ago. Ice sheets formed and glaciers scoured over the continent. In a study that was published last year, German biologists found that the onset of this cooling event coincided with the origin icefish and the evolution of antifreeze proteins.
Why icefish can survive without Haemoglobin?
A larger heart pumps more blood, and wider blood vessels let more blood flow through. These adaptations help blood circulate through the icefish’s body more quickly. This makes it easier for the blood to deliver oxygen to cells, even without hemoglobin.
Why does the icefish have clear blood?
Through the power of natural selection, its descendants developed traits that let them survive these unlikely conditions. Today, the Antarctic blackfin icefish, or Chaenocephalus aceratus, thrives in these frigid waters with no scales, blood as clear as water and bones so thin, you can see its brain through its skull.
Where are the fossils of notothenioid fish found?
There are no unequivocal notothenioid fossils; thus, little is known of the origins of the suborder. Earlier claims of Eocene and Miocene notothenioid fossils from the Antarctic Peninsula and New Zealand have been discounted. The only substantial Antarctic fish fossils are found in Eocene deposits on Seymour Island, near the Antarctic Peninsula.
How are notothenioids different from other vertebrates?
Their kidneys lack the glomeruli characteristic of most other vertebrates. In contrast, the 26 species of notothenioids living outside Antarctic waters rarely encounter freezing seawater, lack AFGPs, and have glomeruli. Three of the eight notothenioid families are primarily non-Antarctic:
How big is the average size of a notothenioid?
Notothenioids have a diversity of sizes and body forms. Most are small fishes, on the order of 1 ft (30 cm) in length, but some species may be as small as 4.3 in (11 cm) or as long as 6 ft (1.8 m). None is highly colored; most have black, brown, or gray mottling on paler backgrounds.
How long does it take for a notothenioid egg to hatch?
Many Antarctic and subantarctic notothenioids breed biennially, with oocytes taking two years to ripen. Eggs are large and yolky and usually are spawned on or near the bottom. Spawning times differ with latitude and between species, ranging from early spring to early winter.