Vertebrates and Chordates

• Vertebrates have an endoskeleton that includes a backbone.
• The backbone functions as support for the dorsal nerve cord and muscle attachment.
• Vertebrates have a distinct skull, which is also known as cephalization.
• Vertebrates can be found in marine, freshwater, and terrestrial habitats.
• Many vertebrates are capable of flight.
• Vertebrates display bilateral symmetry and are segmented.
• Segmentation can be inconspicuous.
• Vertebrates are triploblastic and have a well-developed coelom.
• Vertebrates have closed circulation systems and chambered hearts.
• Most vertebrates are free-living, though some species are ectoparasitic.
• Vertebrates are deuterostomes (like Echinodermata and Chordata).
• Vertebrates mostly reproduce sexually.

Phylum: Chordata

• All chordates have four key characteristics: a notochord, a nerve cord, Pharyngeal gill slits, and a post anal tail.

Phylum Chordata: Nerve Cord

• The nerve cord is a tube that runs dorsal to the digestive tract.
• The nerve cord gives rise to the spinal cord and brain.

Phylum Chordata: Notochord

• The notochord is flexible and extends the length of the organism's body.
• the notochord is a hydrostatic organ.
• The notochord aids in skeletal support.
• Muscles attach to the notochord, which enables lateral bending without shortening, facilitating undulatory movements.
• The notochord is replaced by a vertebral column in most adult chordates.

Phylum Chordata: Pharyngeal Slits

• Function of Pharyngeal slits: Filtering of food, gill supports, and to functions as jaw supports.
• Are the basis for components of ears and tonsils of tetrapods.

Phylum Chordata: Post Anal Tail

• The post anal tail is for locomotion in aquatic species.
• The post anal tail is used for balance, courting, and communication in tetrapods.

Subphylum: Urochordata

• Urochordates, or tail-chordates, are called tunicates and consist of about 3,000 species.
• Tunicates live primarily in the sea and are sessile as adults, but some are free-living.
• Tunicates form a tough, cellulose-containing tunic.
• Only the larval form has all the characteristics of chordates in some groups.
• In adult metamorphosis, the notochord and tail disappear, the nerve cord reduces to a single ganglion.

Subphylum Urochordata: Classes

• There are three classes of Urochordata: Ascidiacea, Appendicularia, and Thaliacea.

Subphylum Urochordata: Acidians or Sea Squirts

• The most common and well-known of the Urochordata.
• Most species are sessile, attached to rocks or other hard substances.
• Have two external projections: incurrent and excurrent siphons.
• Filter feed by drawing water in through the incurrent siphon, trapping and digesting food, and expelling the water through the excurrent siphon.
• Indigestible waste are discharged from the anus.
• Acidians are hermaphroditic, with external fertilization common.
• Acidians are also capable of regeneration.

Subphylum: Cephalochordata

• Cephalochordates, or lancets, are slender, compressed, translucent animals, sized 3-7 cm, They inhabit sandy sediments in coastal waters.
• "Lancets" refers to their bladelike shape.
• Lancets have a slightly swollen tip on the anterior end of their dorsal nerve cord but no true brain.
• Lancets have colorless blood that moves through a ventral vessel.
• The body structure of lancets is similar to tunicates, but with a smaller atrium and mouth.
• As larvae, cephalochordates feed on planktons. as adults, they bury themselves in the sand and filter-feed.
• Lancets pump water out through the atriopore, separate from waste excretion.
• These organisms have segmented muscles that allow them to undulate.
• They use tentacles as sensors.
• The sexes are separate.
• Gametes are released in the atrium before moving through the atripore where fertilization occurs outside of the body.

Subphylum: Vertebrata

• Vertebrates, a large, diverse group, are also known as Craniata.
• Their endoskeleton allows for unlimited body size.
• They have a stiff vertebral column, and a hollow nervous tissue of spinal cord.
• Vertebrates have mouths and anuses.
• All vertebrates possess a tail, at least during some point of development.
• They have chambered hearts.
• Vertebrates vary in size from 7.7 millimeters to 33 meters.
• They make up about 4% of animal species.

The Earliest Vertebrates

• The earliest vertebrates were jawless and fish-like.
• These vertebrates appeared in the Cambrian period.
• These early vertebrates belonged to the group Agnatha (jawless fish).
• The group Agnatha is considered the ancestors of all modern vertebrates.
• Myllokunmingia and haikouichthys are among the earliest known vertebrates, discovered in China.
• These vertebrates were small, fish-like creatures with a notochord, gill slits, and a primitive cranium.
• They lacked jaws, paired fins, and true vertebrae but had cartilaginous skeletal elements.
• Pteraspidomorphs radiated in the Ordovician period.
• They were the early jawless fish with bony head shields for protection.
• Ostracoderms radiated in the Silurian period and were the first vertebrates with bony armor, but still jawless.
• Placoderms radiated in the Devonian period and were the first jawed vertebrates.
• Placoderms were the first to evolve true jaws, which allowed for more efficient predation.
• They had bony plates covering their bodies and were dominant marine predators.

Superclass: Agnatha

• Also called jawless fishes; including approximately 119 species divided between two clades: Myxini (hagfishes) and Petromyzontida (lampreys).
• They lack jaws, internal ossification, scales, and paired finds.
• Characterized by pore-like gill openings and an eel-like body form.
• The skeleton is made of cartilage.
• Agnatha reproduce sexually and are oviparous.
• A key characteristic of Agnatha is a two-chambered heart.
• Predation is common among Agnatha.

Superclass Agnatha: Hagfishes (Myxini)

• Defining trait, hagfishes lack vertebrae.
• They have soft-skinned bodies.
• The eyes are covered with skin, making them blind.
• Hagfishes typically reside in cold, marine bottom waters.
• The distinct species is set aside by the number and position of the gill apertures.
• Hagfish reproduction occurs sexually.
• Hagfishes produce yolk eggs, with no known larval stage.

Superclass Agnatha: Lampreys (Petromyzontida)

• This is a parasitic group with moderately developed eyes and naked skin.
• They are commonly found in marine environments as adults but spawn in freshwater.
• Lampreys swim by undulations of the body.
• Lampreys attach to other fish species to feed on their bodily materials.
• Lampreys produce small eggs that develop directly into larvae and burrow into the muddy bottom of the stream.

Class: Chondrichthyes

• One defining feature of this group is cartilaginous skeletons.
• The skeletons are extensively calcified and lack bones absent.
• The fishes have jaws and polyphydont teeth as well as a large stomach.
• One exception, the chimaeras lack a stomach.
• Their livers are large and filled with oil.
• Chondrichthyes have well-developed brains.
• Senses of smell, vibration (lateral line), electroreception, and vision well developed.
• Possess separate sexes and internal fertilization with claspers.
• They can be oviparous or ovoviviparous, and have no larval stage.
• The species have a high concentration of urea in their blood.
• Possess 5-7 pairs of gills with no swim bladder or lung.

Class Chondrichthyes: Clasper

• Clasper is used during sexual reproduction.
• Is located on pelvic fin of most fish in the class

Class Chondrichthyes: Sub Classes

• Elasmobranchii (sharks, skates and rays) and Holocephali (chimaeras).
• The species are divided into two subclasses.

Class Chondrichthyes: Sharks

• Sharks account for about 45% of the Elasmobranchs.
• Typically predaceous with 5-7 pairs of fill slits and gills with a spiracle behind each eye.
• They use their keen sense of smell to guide them to food.
• Sharks can locate prey from long distances using the lateral line.

Class Chondrichthyes: Rays

• More than half of all elasmobranchs
• The body is flat dorsoventrally and pectoral fins are enlarged.
• They possess gill openings on the underside of the head.

Class Chondrichthyes: Skates

• Defining traits, skates have thicker tails than string rays
• The barb/spike is not located on the tails of skates fish.
• They posses a set of thorns that run along their tail and back

Class Chondrichthyes: Chimaeras

• Instead of distinct teeth, their jaws bear large, flat plates.

Class: Osteichthyes

• Osteichthyes, or bony fishes have internal skeletons as made completely of bones.
• This is the most species rich group of the vertebrates with more than 30,000 living species.
• They posses an operculum covering the gill with bony plates which is attached to muscles.
• Swim bladders are present which aids in buoyancy and has paired fins.
• They reproduce sexually using internal and external (most common) fertilization.
• Development can be oviparous, ovoviviparous or viviparous.

Class Osteichthyes: Caudal Fins

• Some fish from the class display the heterocercal and homocercal fin type

Class Osteichthyes: Sub Class

• Major division: Actinopterygii (ray-finned fishes) and Sarcopterygii (lobe-finned fish).

Osteichthyes: Subclass Actinopterygii (Ray-finned fishes)

• There are over 31,000 species listed as from the ray finned group.
• They're named after the design of their fins.
• The fins are supported by rays of bony spines.
• Muscles are absent (not present inside) the fins.
• The skeleton is often well ossified, scales grow over time, and there is a presence of the swim bladder.
• The skin as composed of scales from ganoid, cycloid, or ctenoid.
• Most of the skin exists from the dermal region and can be naken.
• The sexes are separate, which may lead to hermaphroditism.
• Not ever can reproduce using parthenogenesis.
• Teleost is made from 29600 list for species of existing

Class Osteichthyes: Mudskipper

• Mudskipper are a species from the Osteichthyes

Osteichthyes: Subclass: Sarcopterygii (Lobe-finned fish)

• Paired pectoral and pelvic fin present, consisting of a long fleshy muscular lobe.
• Sexes are separate with fertilization external (lungfishes) or internal (coelacanths).
• Gills are covered by a bony operculum.
• Typically the fish will have a swim bladder.
• It is used primarily for respiration.
• Cosmoid scales are present.
• Modern freshwater forms have lungs, presumably appearing in the fossil freshwater forms as well.
• Scales can grow throughout the life of an individual.
• Almost certainly the amphibian ancestors.

Class Osteichthyes: Lungfish (Sarcopterygii)

• Defining feature, fish use lobe like fins.
• The class is referred to with a suffix "pterygil" to denote their fins

Class Osteichthyes: Coelacanths

• Defining feature, these are fish part of class Osteichthyes and subgroup Sarcopterygil

Class Amphibia

• All amphibians adapted for extended periods on land.
• Defining trait, all species require freshwater, regardless of what they are.
• Most complex habitat requirements are reflected in the complex life cycle of most species.
• All species display 4 limbs with legs attached.
• Respiration is made possible by lungs
• The organism contains cutaneous respiration and all arteries are divided.
• Their skin is soft, and contain pigment cells present.
• Contains 4 limbs, and a large mouth that holds teeth.

Class Amphibia: Caecilians; Order Gymnophiona (Apoda)

• Animals posses features for borrowing and also have small eyes.
• Most Gymnophiona feed on smaller insects.
• Fertilization is made possible through copulatory organ.
• Their eggs are deposited on the floor bed.

Class Amphibia: Salamanders

• The are identified with their tails.
• The organism are omnivores, and will consumer worms, etc.
• This group of the organism can live in fresh water.
• Their eggs will be fertilized internally.

Amphibia: Frogs and Toads

• Commonly found, popular group amongst other amphibians.
• They can reproduce in a tadbole.
• During breeding they are load, which can also be referred to as noise.
• The organisms perch on top of water near a perch.

Class Reptilia

• Reptiles are members of the clade Aminota.
• Early diversification of the amniotes produced three patterns of hole(fenestrae) in the temporal region of the skull (anapsid, diapsid, and synapsid).
• Some adaptations included the Amniotic egg – four membranes (amnion, allantois, chorion, yolk sac), rib ventilation, and desiccation resistant skin.

Class Reptilia (Scales and Scutes)

• Have thick dry skin due for water loss.
• Are ectotherms.
• Contains amniotic membranes.
• Internal fertilization is present.
• Heart consist or 3 chambers, except the crocodilians.
• The organism contains development tissue.

Class Reptilia: Turtles

• Turtles posses jaws for gripping onto the food.
• They are enclosed consists of shells and a carapace.
• During reproduction the shell will determine the sex of the organism
• Size can vary for leatherback organism

Class Reptilia: Lizards and Snakes

• Class Reptilia, is separated into Lacertilla, serpents, and amphisdaenia.
• These classes exist due to sub grouping.

Tuataras (sphenodonta)

• The sub class exhibits both living and extinct traits.
• They are lizards like and they live in enclosed systems

Class Aves

• Have feathers that distinguish from other animal groups.
• Able to modify with wing and limbs to use to do various actions.
• Contains high body heats due to well maintained organs.
• The organism do not contain teeth.
• Contains a good brain to do different task.
• Contain a middle part to move around.

Class Mammalia

• Class Mammalia contains hairs.
• Has a good size brain and high smell sensory's
• They require a copulatory organ
• Are endothermic like class Aves