Introduction
Ostracoderms (shell-skinned) are of several groups of extinct, primitive, jawless fishes that were covered in an armour of bony plates.
They appeared in the Cambrian, about 510 million years ago, and became extinct towards the end of the Devonian, about 377 million years ago. They were quite abundant during the upper Silurian and Devonian periods. Most of fossils of Ostracodermi were preserved in the bottom sediments of freshwater streams.
However, the opinion is sharply divided as to whether their habitat was freshwater or marine.
The first fossil fishes that were discovered were ostracoderms.
The Swiss anatomist Louis Agassiz received some fossils of bony armored fish from Scotland in the 1830s.
The ostracoderms resembled the present day cyclostomes (lampreys and hagfishes) in many respects and together with them constitute a special group of jawless vertebrates, the Agnatha.
Characteristics: They use gills exclusively for respiration but not for feeding . Earlier chordates with gills used them for both respiration and feeding. Ostracoderms had separate pharyngeal gill pouches along the side of the head, which were permanently open with no protective operculum. mostly small to medium-sized fishes, protected by a heavy, bony dermal (derived from skin) armor. bottom-dwellers; filter-feeders or grazers. no paired fins, but many with stabilizing paired flaps on either side of head.
(1) Ostracoderms were the first vertebrates.
(2) They were popularly called armoured fishes.
(4) They lived in freshwater.
(5) They were bottom dwellers.
(6) Their body was fish-like and did not exceed 30 cm in size.
(7) Paired fins were absent.
(8) Median and caudal fins were present.
(9) The caudal fin was of heterocercal type.
(10) The head and thorax were covered by heavy armour of bones. It protected ostracoderms from the giant scorpion like arthropods, eurypterids.
(11) Bony skull was well developed.
(12) Mouth was mostly present on the ventral side.
(13) They were having large number of gill slits.
(14) The nervous system had 10 pairs of cranial nerves.
(15) The head had a pair of lateral eyes, and a median pineal eye.
(16) They were filter feeders, feeding like a vacuum cleaner.
(17) The endoskeleton was either bony or cartilaginous.
Fishes, amphibians, reptiles, and birds have paired pharyngeal ultimobranchial glands that secrete the hypocalcemic hormone calcitonin. The corpuscles of Stannius, unique glandular islets found only in the kidneys of bony fishes, secrete a peptide called hypocalcin.
In aquatic animals such as fish respiration takes place through special respiratory organs called gills, however lung fish respiration takes place through lungs. Gills are present on both the sides of the head of fish. The gills are covered by gill covers also called operculum. When the fish open its mouth, water is drawn into the buccal cavity and passed through the gills. The gills contain special type of cells that absorb the oxygen present in water. The absorbed oxygen is then supplied to all the cells of body through blood. In the cells, oxygen is converted into carbon dioxide and returned back to gills through blood. Ultimately, the gills release the carbon dioxide in water passing through them.
Respiration in Fish
The gills of fish are very efficient; it is estimated gills can extract about 80% oxygen dissolved in water. In addition to the respiratory organs, the gills have an important role in maintaining the right balance of salts in the body.
The chordates are named for the notochord: a flexible, rod-shaped structure that is found in the embryonic stage of all chordates and also in the adult stage of some chordate species.
It is located between the digestive tube and the nerve cord, providing skeletal support through the length of the body.
In some chordates, the notochord acts as the primary axial support of the body throughout the animal's lifetime.
Mollusca of India and need for conservationAshish sahu
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda. The members are known as molluscs or mollusks. Around 85,000 extant species of molluscs are recognized. The number of fossil species is estimated between 60,000 and 100,000 additional species
Introduction
Ostracoderms (shell-skinned) are of several groups of extinct, primitive, jawless fishes that were covered in an armour of bony plates.
They appeared in the Cambrian, about 510 million years ago, and became extinct towards the end of the Devonian, about 377 million years ago. They were quite abundant during the upper Silurian and Devonian periods. Most of fossils of Ostracodermi were preserved in the bottom sediments of freshwater streams.
However, the opinion is sharply divided as to whether their habitat was freshwater or marine.
The first fossil fishes that were discovered were ostracoderms.
The Swiss anatomist Louis Agassiz received some fossils of bony armored fish from Scotland in the 1830s.
The ostracoderms resembled the present day cyclostomes (lampreys and hagfishes) in many respects and together with them constitute a special group of jawless vertebrates, the Agnatha.
Characteristics: They use gills exclusively for respiration but not for feeding . Earlier chordates with gills used them for both respiration and feeding. Ostracoderms had separate pharyngeal gill pouches along the side of the head, which were permanently open with no protective operculum. mostly small to medium-sized fishes, protected by a heavy, bony dermal (derived from skin) armor. bottom-dwellers; filter-feeders or grazers. no paired fins, but many with stabilizing paired flaps on either side of head.
(1) Ostracoderms were the first vertebrates.
(2) They were popularly called armoured fishes.
(4) They lived in freshwater.
(5) They were bottom dwellers.
(6) Their body was fish-like and did not exceed 30 cm in size.
(7) Paired fins were absent.
(8) Median and caudal fins were present.
(9) The caudal fin was of heterocercal type.
(10) The head and thorax were covered by heavy armour of bones. It protected ostracoderms from the giant scorpion like arthropods, eurypterids.
(11) Bony skull was well developed.
(12) Mouth was mostly present on the ventral side.
(13) They were having large number of gill slits.
(14) The nervous system had 10 pairs of cranial nerves.
(15) The head had a pair of lateral eyes, and a median pineal eye.
(16) They were filter feeders, feeding like a vacuum cleaner.
(17) The endoskeleton was either bony or cartilaginous.
Fishes, amphibians, reptiles, and birds have paired pharyngeal ultimobranchial glands that secrete the hypocalcemic hormone calcitonin. The corpuscles of Stannius, unique glandular islets found only in the kidneys of bony fishes, secrete a peptide called hypocalcin.
In aquatic animals such as fish respiration takes place through special respiratory organs called gills, however lung fish respiration takes place through lungs. Gills are present on both the sides of the head of fish. The gills are covered by gill covers also called operculum. When the fish open its mouth, water is drawn into the buccal cavity and passed through the gills. The gills contain special type of cells that absorb the oxygen present in water. The absorbed oxygen is then supplied to all the cells of body through blood. In the cells, oxygen is converted into carbon dioxide and returned back to gills through blood. Ultimately, the gills release the carbon dioxide in water passing through them.
Respiration in Fish
The gills of fish are very efficient; it is estimated gills can extract about 80% oxygen dissolved in water. In addition to the respiratory organs, the gills have an important role in maintaining the right balance of salts in the body.
The chordates are named for the notochord: a flexible, rod-shaped structure that is found in the embryonic stage of all chordates and also in the adult stage of some chordate species.
It is located between the digestive tube and the nerve cord, providing skeletal support through the length of the body.
In some chordates, the notochord acts as the primary axial support of the body throughout the animal's lifetime.
Mollusca of India and need for conservationAshish sahu
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda. The members are known as molluscs or mollusks. Around 85,000 extant species of molluscs are recognized. The number of fossil species is estimated between 60,000 and 100,000 additional species
#SciChallenge2017 Biotope
This presentation describes how life is under water and describes all the things that you can find in the ocean, like fish, coral reefs and many habitats that fish live in.
The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
We all have good and bad thoughts from time to time and situation to situation. We are bombarded daily with spiraling thoughts(both negative and positive) creating all-consuming feel , making us difficult to manage with associated suffering. Good thoughts are like our Mob Signal (Positive thought) amidst noise(negative thought) in the atmosphere. Negative thoughts like noise outweigh positive thoughts. These thoughts often create unwanted confusion, trouble, stress and frustration in our mind as well as chaos in our physical world. Negative thoughts are also known as “distorted thinking”.
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
3. Fish started appearing in the
beginning of the Paleozoic era.
The first of the armored fish
started in the Ordovician through
the Devonian and they ruled the
world during that time. Fish
started out as cartilaginous and
later developed a bone skeleton.
4. The world was completely covered
in water in the Paleozoic. Shallow
seas covered what now are
Ohio, Kansas and other great
plain countries in the U.S. These
shallow seas left well preserved
fossils for us to excavate later.
5. Name:
Group Name: Ostracoderms (shell- skinned)
Scientific Name: Cartilago-anguilla (cartilage eel)
Common name: Sacabambaspis
Length: Average of 30 centimeters long.
Behaviors: The Sacabambaspis could withstand most
attacks because of it’s strong armor. It also could
camouflage.
Traits: The Sacabambaspis was an algae sucker and it’s
predator was the Eurypterid (Sea scorpion).
Climate: The land was very barren and hot on land.
6. The Sacabambaspis appeared 510
million years ago in the middle of the
Cambrian. Sacabambaspis had a bony
plate on the outside of their
cartilaginous body. Their armor covered
their head and upper torso exposing
their back half which was made up of
cartilage.
7. Sacabambaspis had scratches and pieces
knocked out of their armor from predators or
rough terrain. One of the predators that
caused these scratches and dents was the
Eurypterid (sea scorpion). The jaw was non-
existent at this time, the Sacabambaspis were
filter feeders. Their mouth was located either
on the bottom or the front of their head. Fish
such as the Sacabambaspis did not have fins
to flap their way through the water, but were
eel like and swam in an “S” motion.
13. During the Ordivician, a bony vertebral
column began to appear in fish. The fish
began to have complicated structures. The
suspected cause for rapid evolution is the
movement and placement of the continents.
In the beginning of the Devonian nearly all
Ostracoderms were wiped out.
14. Other fish began to show up in huge
quantities after most of the Ostracoderms
were gone. This massive amount of fish gave
the Devonian it’s name, “The Age of Fish”.
Placoderms arrived during the Silurian and
the Devonian replacing the Ostracoderms.
15. Name:
Group name: Placoderms (Armor Skinned)
Scientific name: Auctorrisus (Powerful Bone)
Common name: Dunkleosteus
Length: Up to 33 feet long
Weight: 4 tons (that’s the weight of 4
elephants!!!)
16. During the Devonian, there were two
continents, Gondwana and
Euramerica, located close to each other. A
ocean covered the rest of the globe, and the
land was completely dry. The climate was
relatively warm and dry. There were no
glaciers until the Late Devonian, when ice
began to cover parts of the South Polar
region.
17. The world in the Devonian period
Gondwana, Euramerica and Siberia
18. The armor of the Auctorrisus covered their entire
head and some of their body. Dunkleosteus had
armor surrounding their eyes and had functional
jaws unlike the Sacabambaspis. The
Dunkleosteus did not have “teeth” but had bone
extrusions that connected to the skull. It’s
powerful bite had 11,000 pounds of strength and
if the knives in it’s month concentrate that
strength in a little point of the front it would with
an amazing strength of 80,000 pounds per
square inch. The Great White Shark, only could
bite with half of this strength.
19. The Auctorrisus had no predators so most
people think that the armor was useless, but
scientists think that they were cannibals. The
Dunkleosteus armor was over 2 inches thick.
Unfortunately they only lasted 50 million
years and they branched off to many different
species around the world.
25. There was a mass extinction in the
Devonian and almost all
Dunkleosteus were killed. To
adapt to the dramatic changes the
water, they evolved into
amphibians and roamed on land.
26. Name:
Group name: Crocodilian (crocodile)
Scientific name:Errordentium (maze of teeth)
Common name: Labyrinthodont (maze of
teeth)
Length: Average 15 feet (head to tail)
27. The climate in the
Carboniferous was very hot
and humid. The first forests
started to appear. In the
Carboniferous there were lots
more continents developing.
29. Labyrinthodont were giant amphibians
distantly related to newts and salamanders.
In outward appearance Labyrinthodont
looked much like modern salamanders, but
with two main differences; they had jaws
full of sharp teeth; and they often grew to
enormous sizes.
The smaller Labyrinthodont ate insects and
fish, but the bigger ones sometimes ate
larger animals.
30. The many sharp teeth they had were
useful for catching such things as fish
and perhaps unwary small dinosaurs
that got too close to the water’s edge.
But when the teeth of one good-sized
Labyrinthodont called Siderops kehli
were carefully examined, all that was
found were the fossilized remains of
millipedes and a piece of the backbone
of another Labyrinthodont, meaning
they were cannibals.
31. It had a large head and powerful teeth, but
had a relatively weak body so it hunted food
underwater, and ate land animals at the
water's edge, much like a crocodile would. To
capture small prey in the water, all it needed
to do was to open its mouth, and the rush of
water would have sucked prey straight in.
Strange enough, it’s teeth indicate that
Labyrinthodont was not content on sucking up
small prey.
37. You might be wondering, what
happened to the Labyrinthodont
between the time they evolved and the
mass extinction? The answer is
nothing. The Labyrinthodont did not
have a reason to evolve, so they
stayed the same.
38. The mass extinction wiped out 90-95%
of marine animals. This was it’s main
diet and was the only thing that young
Labyrinthodont eat and adults also ate
fish. The lack of food caused all
Labyrinthodont to die out.
39.
40. Arreola, Freddie. “The Evolution of Armored Fish”.
Cochise College Geology . Weller, Roger. Spring 2005.
October 2011
<http://skywalker.cochise.edu/wellerr/students/arm
ored-fish/armored-fish.htm>
“Labyrinthodont”. JoyZine. 2009. November 2, 2011
<http://www.artistwd.com/joyzine/australia/articles/
dinosaurs/labyrinthodont.php>
41. “The Permian Mass Extinction”. Park.
November 7, 2011
<http://park.org/Canada/Museum/extinctio
n/permass.html>
Burton, Virginia. Life Story. Burton Virginia, 1962
