Chordates

Early agnatghons were small, less than _____ in length.

50 cm

How many lineages are the Gnathostomes divided into and what are they?

8:Chondrichthyes, Actinopterygii, Actinista, Dipnoi, Amphibia, Reptilia, Aves, and Mammalia.

Gas Exchange in Osteichthyes?

Occurs by drawing water over the four or five pairs of gills located in chambers covered by an operculum.

Describe the Neural Crest.

A group of embryonic cells found only in vertebrates, contributes to the formation of certain skeletal components and many other structures that distinguish vertebrates from other chordates. The dorsal, hollow nerve cord develops from an infolding of the edges of an ectodermal plate on the surface of the embryo.

What is the Notochord?

A longitudinal, flexible rod located between the gut and nerve chord. It is present in all chordate embryos, composed of large, fluid-filled cells encased in a stiff, ibrous tissue, and extendds through most of the length of the animal as a simple skeleton.

Describe the Vertebral Column

A skeleton including a cranium and vertebral column are the main axis of the body, replacing the notochord as the basic skeleton.

What are Muscular Postanal Tails?

A tail extending beyond the anus, it is found in most chordates and contains skeletal elements and muscles. Provides much of the propulsive force in many aquatic species.

What are two subgroups of Vertebrata?

Agnatha-Jawless Vertebrates Gnathostomata-Jawed Vertebrates

What lineages make up the Tetrapod Vertebrates?

Amphibia, Reptilia, Aves, and Mammalia.

What does it mean to be a Tetrapod?

An animal possessing two pairs of limbs that support it on land.

What are the two skeleton types?

Axial-Head and Vertebral Column Appendicular-"Appendages" every other bone

What are the Osteichthyes?

Bony Fishes. ?They are abundant in marine and freshwater, the skeleton is bony, reinforced with a matrix of calcium phosphate, skin is covered with flattened bony scales, skin glands produce mucus that reduces drag when swimming, and a lateral line system is present as a row of tiny pits in the skin on both sides of the body.

What are hallmarks of the Osteichthyes?

Bony endoskeleton, operculum, and a swim bladder.

Example of Cephalocordata?

Branchiostoma(Old name Amphioxus)

Who are the Lancelets?

Cephalochordata-due to their bladelike shape.

Are cephalochordates filter feeders? If so how?

Cephalochordates are filter feeders. The burrow tail first into the sand with only the anterior exposed. Water is drawn into the mouth by ciliary action and food is trapped on a mucous net secreted across the pharyngeal slits. Water exits through the slits and trapped food passes down the digestive tube.

A Cartilaginous endoskeleton reinforced by calcified granules is diagnostic of what lineage?

Chondrichthyes

Early Gnathostomes included ancestors of what lineage?

Chondrichthyes and Osteichthyes as well as a now extinct group of armored fish known as Placoderms.

Describe Cephalochordates

Chordate characteristics are prominent and persist in the adult (all 4 chordate characteristics).

What are the 4 anatomical features that characterize the lineage Chordata?

Chordates are deuterostomes with four unique characteristics which appear some time during the animal's life. These characteristics are the notochord, a dorsal, hollow nerve cord, pharyngeal slits, and a muscular postanal tail.

What are Pharyngeal slits?

Chordates have a complete digestive system (mouth and anus). The pharynx is the region just posterior to the mouth and it opens to the outside through several pairs of slits. The presence of the slits permist water entering the mouth to exit without passing through the entire digestive system. Function for suspension-feeding in invertebrate chordates. They have become modified for has exchange and other functions during the evolution of vertebrates.

Another name for the Amniotic Egg?

Cleidoic Egg

Vertebrata are also known as?

Craniata

What is the Dorsal, Hollow Nerve Cord?

Develops in the embryo from a plate of dorsal ectoderm that rolls into a tube located dorsal to the notochord. Unique to chordates; other animal clades have solid, usually ventral nerve cords. The brain and spinal cord(CNS) develops from this nerve cord.

In what time period where early agnathans gradually replaced by vertebrates with jaws(Gnathostomata)?

Early Devonian

Are Lampreys Ectoparasitic or Free living?

Ectoparasitic

Discribe Lampreys

Eel-shaped, feed by clamping their round mouths onto live fish. Once attached, they use a rasping tongue to penetrate the skin and feed on the prey's blood. Sea lampreys spend their larval development in freshwater streams and migrate to the sea or lakes as they mature.

Discribe Heart Types in Vertebrates

Fishes(2Chambered)->Amphibians(3)->Reptiles(Imperfect4)->Birds(4)->Mammals(4)

Describe Chondrichthyes

Flexible skeletons composed of cartilage, well-developed jaws and paired fins. The ancestors of which had bony skeletons. The characteristic cartilaginous skeletons is thus a derived characteristic, having evolved secondarily. The cartilaginous skeleton is more elastic and lighter than a bone skeleton.

Are Hagfish Ectoparasitic or Free living?

Free Living (Exclusively Marine)

What is a prehensile tail?

Grasping Tail (including snakes)

Describe Hagfish

Hagfished superficially resemble lampreys. They are scavengers without rasping mouthparts. Some species will feed on sick or dead fish while others feed on marine worms.

Describe Sharks

Have streamlined bodies and are swift swimmers. The tail provides propulsion, the dorsal fins serve as stabilizers, the pectoral and pelvic fins produce lift, and some buoyancy is provided by large amounts of oil stored in the liver, but most swim continuously to remain in the water column.

Were did vertebrate Jaws come from?

Hinged jaws evolved as modifications of the skeletal rods which previously supportd the anterior pharyngeal gill slits.

What were the oldest fossils of vertebrates?

Jawless animals found in rock strata.

Describe pre-cambrian/cambrian agnathans.

Jawless with oval slitlike mouths; most lacked paired fins and were bottom-dwellers. Some were active and had paired fins. Were probably bottom- or suspension-feeders that trapped organic debris in the gill slits.

What are the only 2 Extant Agnathas?

Lamprey and Hagfish.

List the synapomorphies that distinguish vertebrates from urochordates and cephalochordates.

Neural Crest, pronounced Cephalization, a Vertebral Column, and a closed circulatory system.

Purpose of a Gas Bladder in Osteichthyes?

Located dorsal to the digestive tract, provides buoyancy. Transfer of gases between blood and swim bladder varies bladder inflation and adjusts the density of the fish.

What are two examples of Urochordata?

Molgula and Ciona

What is another name for egg-laying mammals? What are they?

Monotremes:Platypus and Echidna

Describe Urochordata

Most are sessile marine animals that adhere to rocks, docks, and boats. Some species are planktonic while others are colonial. The tunicates are filter feeders. Adult tunicates bear little resemblance to other chordates. Larval tunicates are free swimmers and possess all four chordate characteristics.

Reproduction in Bony Fish?

Most bony fish are oviparous and utilize external fertilization.

Describe Placoderms

Most were less than 1m in length but some were up to 10 m long. Differed from agnathans in that they possessed paired fins and hinged jaws. The paired fins enhanced swimming ability and hinged jaws allowed more varied feeding habits including predation.

Why do Vertebrates have unique features?

Probably evolved in association with increased size and more active foraging for food. The more active the lifestyle, the larger the amounts of organic molecuels necessary to produce energy. Vertebrates have several adaptations for feeding, digestion and nutrient absorption. For example, muscles in the walls of the digestive tract move food from organ to organ along the tract.

Example of an Osteichthyes?

Rivulus marmoratus

Describe the tunicates Filter Feeding

Seewater enter through an incurrent siphon, passes through the lits of the pharynx into a chamber called the atrium, and exits via na excurrent siphon, the atriopore. Food filtered from the water by a mucus net of the pharynx is moved by cilia into the intestine. The anus empties into the excurrent siphon.

Whats an example of a Chondrichthyes?

Sharks

Describe Shark Senses

Sharks possess sharp vision (cannot distinguish color) and olfactory sense that are adaptations to their lifestyle. Electric sensory regions that detect muscle contractions of prey are located on the head. A "lateral line system" is present along the flanks. It is composed of rows of microscopic organs sensitive to water pressure changes and detects vibrations.

Shark Reproduction?

Sharks reproduce sexually with internal fertilization. A pair of claspers on the pelvic fins of males transfers sperm into the female reproductive tract. Some species are oviparous, some are ovoviviparous, and a few are viviparous. A cloaca(common chamber for reproductive, digestive, and excratory systems) is present.

Who are the Tunicates?

Species in the Urochordata are commonly called tunicates. The entire animal is cloaked in a tunic made of a celluloselike carbohydrate. AKA Sea Squirts!

Why do adult Tunicates bear little resemblance to other chordates?

They lack a notochord, a nerve cord and tail. They possess only pharyngeal slits.

Describe the Sharks digestive tract

Teeth evolve as modified scales. The digestive tract is proportionately shorter than in other vertebrates. A "Spiral Valve", which incerease surface area and slows food movement, is present in the intestine.

The Devonian is also known as?

The Age of Fishes

When did Ostracoderms and most other agnathans disappear?

The Devonian

Describe Cephalization in Vertebrates

The brain and sense organs are located at the anterior end which is the portion of the body which is in contact with the most environmental stimuli.

How do reptiles, birds, and mammals differ from amphibians?

They have an extra adaptation for terrestrial life known as the amniotic egg(a shelled, water resistant egg) which allows for a complete life cycle on land. Most mammals do not lay eggs but retain other features of the amniotic condition.

What is Arboreal?

Tree Dwelling

The lineage Chordata includes three subgroups which are?

Two invertebrate subgroups: Urochordata, Cephalochordata; and the subgroup Vertebrata.

Describe the Circulatory System in Vertebrates

Vertebrates have a closed circulatory system composed of a ventral chambered (two to four) heart, arteries, capillaries, and veins. The hear pumps the blood through the system. The blood becomes oxygenated as it passes through the capillaries of the gills or lungs.

Do cephalochordates more closely resemble urochordate larvae than adult urochordates?

Yes

Describe Rivulus marmoratus

is a self-fertilizing hermaphrodite. Some are ovoviviparous or viviparous and utilize internal fertilization. Some display complex mating behavior. Most likely originated in fresh water. The swim bladder was modified from lungs of ancestral fishes which supplemented the gills for gas exchange in stagnant water.