Table of Contents
- 1 During which era did the diversification of mollusks occur?
- 2 How do blood groups evolve?
- 3 When did cephalopods evolve?
- 4 What makes blood types different from each other?
- 5 Did cephalopods evolve from mollusks?
- 6 Why do mollusks have better preserved fossils than other early organisms?
- 7 How did the cephalopod shell evolve?
- 8 What animals are in the cephalopod group?
During which era did the diversification of mollusks occur?
Cambrian
Mollusks diversified during the Cambrian, and by the end of the Cambrian, 490 mya, it is likely that all classes of mollusks had been established (Gonzalo Giribet, personal communication).
When did Mollusca appear?
about 545 million years ago
Mollusks have been diverse and abundant animals since earliest Cambrian time (about 545 million years ago = mya), and predate the appearance of trilobites in the fossil record.
How do blood groups evolve?
Human blood types most likely came to exist to fend off infectious diseases. The incompatibility of some blood types, however, is just an accident of evolution. There are four main blood types. Blood type A is the most ancient, and it existed before the human species evolved from its hominid ancestors.
Why did different blood types evolve?
“The short story is that blood types probably evolved as a way to fight infectious diseases or other environmental pressures,” she said. “Blood types that survived were more likely to be successful.” In a way, it’s all about survival of the fittest blood.
When did cephalopods evolve?
Cephalopods evolved during the Cambrian (∼530 Ma) from a monoplacophoran-like mollusc in which the conical, external shell was modified into a chambered buoyancy apparatus. During the mid-Palaeozoic (∼416 Ma) cephalopods diverged into nautiloids and the presently dominant coleoids.
Why are mollusks a good system for the study of the evolution of complex features?
Because of the hard outer shell that is present on most mollusks, they are well-preserved and have a long and abundant fossil record. Mollusks have also evolved several structural features that are unique to the species of this phylum and do not persist in higher invertebrates.
What makes blood types different from each other?
Blood types are determined by the presence or absence of certain antigens – substances that can trigger an immune response if they are foreign to the body. Since some antigens can trigger a patient’s immune system to attack the transfused blood, safe blood transfusions depend on careful blood typing and cross-matching.
Why is blood group different?
The system for classifying them came about in order to allow safe blood transfusions. Like all cells, red blood cells have molecules on their surface called ‘antigens’. People have different antigens, depending on their genes.
Did cephalopods evolve from mollusks?
Cephalopods evolved during the Cambrian ($530 Ma) from a monoplacophoran-like mollusc in which the conical, external shell was modified into a chambered buoyancy apparatus.
How do cephalopods evolve?
The cephalopods were once thought to have evolved from a monoplacophoran-like ancestor with a curved, tapering shell, and to be closely related to the gastropods (snails). The earliest such shells do not have the muscle scars which would be expected if they truly had a monoplacophoran affinity.
Why do mollusks have better preserved fossils than other early organisms?
Because of the hard outer shell that is present on most mollusks, they are well-preserved and have a long and abundant fossil record. Like the more primitive roundworms, mollusks have a complete digestive system and a nervous system.
What is the circulatory system of cephalopods?
Cephalopods are the only mollusks that have closed circulatory system, which the blood contains food and oxygen that moves through the body in a series of closed vessels. Just like a human’s blood that moves through their blood vessels.
How did the cephalopod shell evolve?
By the Ordovician, a period that began roughly 500 mya, a great diversity of cephalopod shells emerged. The stout, slightly curved shell shapes of the late Cambrian evolved into a variety of shapes that included coils, straight cones and domes.
Which mollusks have closed circulatory system?
Squid and octopuses have a well-developed nervous system and large eyes which are similar to human eyes. Cephalopods are the only mollusks that have closed circulatory system, which the blood contains food and oxygen that moves through the body in a series of closed vessels. Just like a human’s blood that moves through their blood vessels.
What animals are in the cephalopod group?
The animals in this group are squid, octopuses, cuttlefish, and chambered nautiluses. The word cephalopod means “head-footed” and describes the body structure of the invertebrates. Cuttlefish, like most cephalopods, have a large and well-developed head.