lab 7: chordates

Name the four characteristics that all chordates share at some point of their life cycle.

• Dorsal hollow nerve cord

• Notochord

• Postanal tail

• Pharyngeal gill slits

What is teh structures of the characteristic of the Phylum Chordata: Notochord, Pharyngeal gill slits, Postanal tail, Dorsal hollow nerve cord.

Phylum Chordata includes organisms with different body plants; however, they all share characteristics at some point of their life:

• Notochord, which is flexible cartilage rows on the dorsal (back or posterior) side that supports the body, anchors, internal muscles and allows rapid, versatile movement. This becomes the vertebrae within Subphylum Vertebrata

• The nervous system develops from a dorsal hollow nerve cord. This lies dorsal to the notochord. In vertebrates, the dorsal hollow nerve cord differentiates into the brain and spinal cord

• Pharyngeal gill slits connect the pharynx, muscular tube that links the mouth cavity and their esophagus, with the outside

• A postanal tail that extends beyond the anus, at least during their embryonic development

Describe what it means to be ovoviviparous

When an egg is hatched inside, then live birth follows

Describe what is means to be viviparous

Develop inside the mother and born alive

Describe what it means to be oviparous

Lay eggs that develop and hatch from egg

In vertebrates, a unique group of embryonic cells called the ( ) contributes to the development of many vertebral structures

neural crest

Vertebrates have ( ) which are often paired and can include fins, legs, forelimbs, or hind limbs

Jointed appendages

Select the correct answer: Perch have (no/ dermal / placoid) scales

Dermal

Vertebrates possessing true jaws known as

Gnothostomes

How many chambers does a frog have?

3

In bony fish, the ( ) is a gas filled organ that help fish maintain their buoyancy and position in the water column

Swim bladder

Identify the Phylum

Phylum Chordata

List and identify the subphylum

The three subphyla of Phylum Chordata are:

1. Subphylum Urochordata (Tunicates)

• Marine animals.

• Adults are usually sessile (attached in one place), while larvae can swim freely. As adults they exhbit major body cavity.

2. Subphylum Cephalochordata (Lancelets)

• Scaless, fish-like marine animals.

• The notochord extends the entire length of the body and remains throughout life.

• Often live partially buried in shallow water throughout the oceans of the world

3. Subphylum Vertebrata (Vertebrates)

• Animals with a vertebral column (backbone) and cranium (skull).

• Have an internal skeleton made of cartilage or bone.

• Examples: fish, amphibians, reptiles, birds, and mammals.

Subphylum Urochordata (Tunicates)

Tunicates are a group of marine animals, sessile as adults, with free swimming larvae. 

Marine animals. As adults they exhbit major body cavity.

Subphylum Cephalochordata (Lancelets)
Structures

Has notochord run down entire length of the dorsal nerve cord and perist throughout the animal life.

lancelet have many pharyngeal gill slits, lack pigment in their skin, and their body is pointed at both ends

Subphylum Vertebrata (Vertebrates)

Structures

Vertebrates have evolved several advanced features associated with increasing body size and mobility. These include:

• Vertebral column: notochord is replaced during the course of embryonic development by a body vertebral column that encloses and protects the dorsal hollow nerve cord

• Cranium: well differentiated head, with a skull and brain

• Endoskeleton: made of cartilage or bone.

• Neural crest: a unique group of embryonic cell called the neural crest contributes to the development of many vertebrate structures

• Internal organs: both their circulatory and their excretory functions

• Joint appendages: the two pairs of appendages that can include fins, wings legs, legs, forelimbs, or hind limbs

Identify the Clade

• Clade Cyclostomata

• Clade Chondrichthyes

• Clade Osteichthyes

• Clade Amphibia

• Clade Reptilia

• Clade Aves (birds)

• Clade Mammalia

Clade Cyclostomata: Jawless Fishes

Structures

Clade Cyclostomata is not the only group without jaw, also superclass include lamprey and hagfish

• All members of Cade Cyclostomata share the following common characteristics:

  • Jawless

  • Cartilaginous skeleton

  • No paired fins

  • Single nostril

  • No scales

  • Two chambered heart 

• All remaining members of vertebrates are gnathostomes (possess true jaw)

Clade Chondrichthyes: Cartilaginous Fishes

Include sharks, skates, and rays. Most are marine

• All have:

  • Jaws

  • Cartilaginous skeleton

  • Placoid scales

  • Paired fins

  • Nars (paired nostrils)

• The male possess claspers (specialized structure used for sperm transfer during mating)

• Birth in this group can be:

  • Viviparous (live birth)

  • Oviparous (hatched from egg)

  • Ovoviviparous (when the egg is hatched internally, followed by live birth)

• Caudal fin (fin at the very end of the organism) much longer than the ventral

Clade Osteichthyes: Clade Actinoterygii and Sarcopterygii 

• This group consists of body fish. Many bony fishes are streamlined and fusiform (tapered at both end) for locomotion and are covered in dermal scales (some don't have scales)

• Their gills are used for gas exchange and the lateral line along the body is a sensory organ that detects vibration in the water that help fish detect and follow prey, avoid predators, participate in schooling behaviors, and sense changes in water flow or pressure.

• The swim bladder is a gas filled organ that helps fish maintain their buoyancy and position in the water column. By adding or removing gas from the swim bladder, fish can have a positive buoyancy and position in the water column.

• Most bony fish have bone rays that make up the majority of the fin, placing them into Clade Actinopterygii.

• The Clade Sarcapterygii contains the Lungfish and coelacanths. 

Clade Amphibia

• Transition from life in water to life on land is Clade Amphibia. These include frogs, toads, salamanders, newts, and caecilians.

• Primary characteristics of this group include four legs, with four toes on each foot. 

• There are three possible types of respiration in this group:

  • Lungs (typically only in adult stages

  • Through the skin

  • With gills (typically only in larval stages)

• Have three chambered heart

• Amphibians are ectothermic (must regulate their body temperature by moving to different microclimates

Clade Reptilia

• Reptiles were the first group to evolve the amniotic egg. These self contained eggs with leathery or calcified shells allow animals to bypass the larval stage. The amniotic egg, fertilized internally, allows gas exchange across the shell (chorion), but protects the developing embryo from water loss.

• Reptiles are ectothermic and use solar radiation to regulate their body temperature. Reptiles have stronger skeleton (support larger body), narrow skulls, three-to four-chambered heart, and protective dry scales that retard water loss and allow them to live in dry habitats

Clade Aves: Birds

• Clade Aves is nested within Clade Reptilia. However, the significant differences between reptiles and birds cause scientists to consider birds separate from the reptiles.

• Birds and mammals are endothermic (regulate their internal temperature without regard to external environment temperature)

• Birds have a four-chambered heart 

• Birds have three types of feather: 

  • The contour (flight feathers)

  • Down feathers (fluffy and used for insulation)

  • Filoplumes feathers (stiff shaft, with occasional barbs at the top)

Clade Mammalia

• Mammals include many of the animals that are familiar to us: humans, monkey dogs, cats, bears, horses, cows, deer, squirrels, porcupines, beavers, rabbits, elephants, rhinoceri, kangaroos, dolphins, and bats.

• Early mammals were quadrupedal (four footed) and have five digits one each limb

• Modern mammals have body hair (at some stage of development), two pairs of appendages, mammary glands that produce milk for nourishment of newborns, have internal fertilization, and most are viviparous. 

• Mammals are endothermic and regulate their own body temperature

• Mammals have large well developed brains; a four-chambered heart; lungs; teeth; kidney

• The mammals are divided into three sub-group:

  • Monotremata (monotremes): possess all characteristics of mammals, but have oviparous birth (lay eggs) and have a cloaca (single opening where digestive, excretory, and reproductive system all discharge)

  • Metatheria (marsupials): referred to as pouched mammals. 

  • Eutheria (placental mammals): born fully developed after long period of gestation where nutrients and gas exchange occurs between the mother and the developing embryo (placenta).

Subphylum Urochordata

Tunicates

Subphylum Cephalochordata

Lancelet

Clade Cyclostomata

Jawless fish

Clade Chondrichthyes

Cartilaginous fish

Clade Osteichthyes

Bones fish

Clade Amphibia

Clade Reptilia

Clade Aves

Birds

Clade Mammalia