LABORATORY EXERCISE VIII
PHYLUM CHORDATA
All chordates, at some time during their lives, possess a notochord , a dorsal hollow nerve chord , and pharyngeal clefts . The notochord is a slender skeletal rod located between the
85 nerve cord and the digestive tract. The urochordates, the cephalochordates, and the vertebrates compose the Phylum Chordata.
SUBPHYLUM UROCHORDATA tunicates
CLASS ASCIDIACEA sea squirts
Only the larval stage, called a tadpole larva, possesses the three chordate characteristics.
The only chordate characteristic maintained by adults are the pharyngeal clefts.
Ascidian Tadpole larva Slide (Box V; slide tray 9; 10x)
Why do you think this is called a tadpole larva? Can you think of a logical hypothesis as to how other chordates may have evolved from a urochordate like ancestor?
These sessile tunicates can usually be recognized by their spherical or cylindrical shape and their two siphons . Some are solitary and some, colonial.
Sea squirt diversity
Be able to recognize the specimens on demonstration as sea squirts.
Note their two siphons.
Ecteinascidea Slide (Box V; slide tray 9; 4x)
Notice the pharyngeal basket that contains the clefts.
SUBPHYLUM CEPHALOCHORDATA amphioxus
These animals are frequently found in subtropical, sandy, marine areas. As adults, they possess all three of the chordate characteristics.
Brachiostoma lanceolatum (amphioxus) specimen
Amphioxus is the common name of this species. Be able to recognize these specimens as cephalochordates.

Brachiostoma lanceolatum (Amphioxus) Slide (Box V slide tray 10; 4x)
Be able to identify the structures labeled in the diagram.
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SUBPHYLUM MYXINI hagfishes
The Myxini are unique among living chordates in that they have a partial cranium (skull), but no vertebrae, and so they are not truly vertebrates
—they are an example of craniates which are not vertebrates.
Hagfish
Notice the structure of the mouth and the lack of paired appendages in this cyclostome.
SUBPHYLUM VERTEBRATA vetebrates
The vertebrates are the most numerous and most familiar chordates. The three chordate features
—notochord, dorsal hollow nerve chord, and pharyngeal clefts—are found in the developmental stages of all vertebrates. The subphylum includes the fish-like vertebrates, the amphibians, the reptiles, which include the birds, and the mammals.
EXTERNAL STRUCTURE OF FISH-LIKE VERTEBRATESKnow the features indicated in the diagram. No single fish possesses all these characters, but you should be able to find all of them among the specimens provided.

The first of the fish-like vertebrate classes contains organisms with no jaws. In addition, they
87 do not have paired fins. At one time the lampreys and the hagfishes were placed in the same class because neither animal have jaws and both have circular mouths.
CLASS PETROMYZONTIDA lampreys
Ammocoetes larva of a lamprey Slide (Box V slide tray 10; 4x)
Because lampreys are anadromous — adults travel from the ocean to fresh water to spawn — The ammocoete larva are found in streams. These larvae are not parasitic. They lack the sucker mouths of the adults and feed by producing strands of mucus and trapping food particles.
Lamprey specimens
Notice the circular, sucking mouth and the numerous teeth of these parasitic fish. Notice also that there are no paired fins.
CLASS CHONDRICHTHYES cartilaginous fishes
The second class of fish-like vertebrates contains organisms with jaws , paired fins , and a cartilaginous skeleton . Sharks, rays, skates, and chimaeras are in this class.
SUBCLASS ELASMOBRANCHII sharks, rays, skates
The rough skin of elasmobranchs is caused by the toothed placoid scales that cover their bodies. There are five to seven external openings for the gills, and there is no covering, or operculum, over these. Most elasmobranchs also have an unevenly lobed, i.e., heterocercal , tail.
Placoid scales (Box V slide tray 11; 10x)
Shark scales are derived from the same epidermal tissue as their teeth. The scales are continually replaced and are composed of enamel overlying dentine .
Sharks: preserved dogfish and jaw of unknown shark
Feel the skin, locate the gill openings.
Note the teeth in the shark jaw; you should be able to see the rows of replacement teeth.

Ray
Where are the gill openings on this elasmobranch? All rays have a barb on the tail. Do not touch the barb! The wings of rays are modified pectoral fins.
Skate
Where are the gill openings on this elasmobranch? Skates have no barb on the tail. Their wings are modified pectoral fins.
Skate egg case
The egg cases of skates are found washed up on beaches around the
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SUBCLASS HOLOCEPHALI chimaeras or ratfishes
Chimaera
The many odd structures on this deep sea chimaera distinguish it from all other fish.
CLASS OSTEICHTHYES bony fishes
The organisms in the third and last class of fish-like vertebrates have jaws , paired fins , and a skeleton with at least some true bone .
SUBCLASS ACTINOPTERYGII ray-finned fishes
The base of the fins is rayed and not fleshy. There are three superorders of ray-finned fishes, and the bases for taxonomic differentiation are mainly the amount of skeleton that is bone and the type of external scales. We will cover only one of the superorders, the Teleostei.
SUPERORDER TELEOSTEI higher bony fishes
The skeleton is mostly bony in these ray-finned fishes, and the scales are usually cycloid or ctenoid . Most of the common fishes are in this superorder; representatives of many of the more common and well-known orders, along with distinguishing features, are covered in this part of the laboratory exercise.

Cycloid scales (Box V slide tray 11; 10x)
These essentially round scales increase in size as the fish grows. As a consequence, in some species the scales are marked by growth rings.
Ctenoid scales (Box V slide tray 11; 4x)
The free, posterior margins of these scales possess a number of comb-like projections. Ctenoid scales are most often found on fishes possessing spiny dorsal fin rays.
Order Cypriniformes minnows, catfishes, suckers, carp, shiners, chubs, dace
Catfish
Notice the barbels on the chin; also, there are no visible scales.
Bala “Shark” specimen
These common aquarium fish are not sharks but bony fish. Their torpedo shape and large dorsal fin is why they are called “sharks”. They are actually native to rivers from S. E.
Asia, including the famous Mekong river.
Order Anguilliformes eels
Eels have elongated bodies and continuous fins.
American eel
The american eel is found on the east coast of the U.S. The female spawns in salt water, and it takes 9 to 10 weeks for the eggs to hatch. After hatching, young eels enter freshwater systems to mature.
Moray
Moray eels frequent tropical and subtropical coral reefs. Their small circular gills, located on the flanks posterior to the mouth, require the moray
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to constantly open and close their mouth to facilitate respiration. This give them a menacing look and a commensurate underserved bad reputation.
Order Perciformes perch, bass, sunfish, sculpins
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Most members of this order have two dorsal fins, the first one of which is very spiny. The two fins may be attached or separate.
Perch Perca specimen
Like all members of the
Perciformes, Perch have ctenoid scales. The Yellow perch ( Perca flavescens ), is found in the United States. Perch are popular with fisherman, they go after all types of bait but often swallow the hook!
Sunfish
The common sunfishes, which are also called bluegill or pumpkinseed fish, are widely distributed throughout the lakes and rivers of the United States and Canada.
Order Pleuronectiformes flatfishes
The body is very flat and the eyes are on one side of the body.
Flounder
Flounder lie on their sides on the ocean floor. Flounders are born ( or hatched ) with one eye on either side of their head, like any normal fish; however, during the course of early development, one eye migrates over the top of the head.
Order Muligiformes barracudas, mullets, silversides
The pelvic fin contains five rays preceded by a spine.
Barracudas
Notice the teeth! This species has a bad reputation but as long as

you don’t where shiny jewelry or provoke them, they won’t cause you a problem.
Order Gasterosteiformes sea horses
Sea horses
Sea horses are notable for being one of only a few species where the males get pregnant.
When mating the female aligns a long tube called the ovipositor with the male's pouch.
The eggs move through the tube into the male's pouch where he then fertilizes them.
The seahorse is a true fish, with a dorsal fin and pectoral fins located on the head near their gills.
CLASS AMPHIBIA amphibians
The life cycle of most species includes a larval aquatic stage, the tadpole . Adult amphibians
91 usually possess toed limbs and have a moist skin lacking scales, but with many glands. The class includes the frogs, toads, and salamanders.
Order Anura frogs and toads
Frogs and toads have no tails. Their hind limbs are elongated for jumping. Frogs usually have smoother skins and fewer obvious glands than toads.
Family Bufonidae toads
The glands of toads are among the most prominent of the amphibians. They give the skin of toads its characteristic "warty" appearance.
Toad Bufo
Behind their eyes, you can find a wartlike structure, the paratoid glands .
These glands, which secrete a white, poisonous substance distinguish the true toads from all other tailless amphibians.
Family Hyalidae tree frogs
Very smooth skin and expanded disks on the toes characterize the tree frogs.
Tree frogs
Be able to recognize this specimen as a tree frog.

Family Ranidae true frogs
Like tree frogs, true frogs all have smooth skin, but there are no expanded disks on the feet.
Rana tadpole
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Like most anuran tadpoles, the tadpole of the genus Rana lacks arms, swims with a fish-like undulating motion, breathes with external gills and senses vibrations by means of lateral lines .
Even their heart has only two chambers
Like that of fish!
Rana adult
These true frogs are characterized by their slim waists and smooth skin.
They are excellent jumpers due to their long slender legs.
Order Caudata (Urodela) legged and tailed amphibians
The tailed bodies are elongate and the hind limbs are not modified for jumping. This order is very well represented in eastern North America.
Family Cryptobranchidae giant salamanders
Hellbender
A glance at this large amphibian should suffice for all future identifications!
Family Ambystomidae mole salamanders
Distinct vertical grooves on the body between the legs, called costal grooves , are the distinguishing feature of these medium sized salamanders.
Spotted salamander
Notice the costal grooves.
Family Salamandridae newts
Newts have somewhat stout, medium-sized bodies with indistinct costal grooves.

Newt Diversity
Be able to recognize these specimens as newts.
CLASS REPTILIA reptiles and birds
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Members of this class of vertebrates have no larval stages. All development occurs within the egg. The skin is dry, scaly, and without glands. The Reptilia includes turtles, lizards, snakes, crocodilians and birds.
Order Chelonia turtles
The soft body parts of turtles are bordered top and bottom by two shells -- the upper carapace and the lower plastron .
Family Chelydridae snapping turtles
The plastron is small and the upper surface of the tail is toothed.
Snapping turtle
Snapping turtles are noted for their powerful beak-like jaws. Their necks can reach two-thirds the length of their body, making handling potentially dangerous. They may live for 50 years or more.
Family Emydidae common turtles
Almost any turtle found in the United States that has a hard shell, no barbels, and a fully developed plastron is a member of this family. Two common examples are on display.
Cooter and slider
Cooter turtles are common in the southeastern U.S. The word "cooter" stems from kuta , the word for turtle in the Bambara and Malinké languages, brought to America by African slaves.
Slider turtles are abundant in the ponds and streams of the Southeast.
Order Squamata lizards and snakes
Suborder Lacertilia lizards
These terrestrial reptiles have elongated bodies and paired limbs. The presence of scales and claws (on most) distinguishes them from salamanders.

Family Gekkonidae geckos
Geckos usually have prominent eyes and ridged toes called clinging pads.
Gecko
Notice the clinging pads.
Family Iguanidae iguanids
Iguanids form a very large family that is well-developed in the New World.
Anolis or green chameleons
The anoles are the only native eastern U.S. iguanids. Notice the relatively smooth appearance.
Iguana
Iguanas are well-known lizards from the American tropics.
Family Scinidae skinks
Relatively smooth, the skink has a rather undefined neck.
Skink
Skinks look roughly like iguanids, but most species have no pronounced neck and relatively small legs
Suborder Serpentes snakes
Serpents have very elongate, limbless bodies.
Family Boidae boas
Boa tail
Boas are a plesiomorphic family of snakes; they have vestigial posterior appendages called spurs. The spurs are located near the anal opening or vent.
Family Colubridae colubrids
In North America most of the harmless snakes are in this family.
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Garter snake
Garter snakes are very common across North America, and are an everyday find in gardens. The pattern on these snakes consists of one or three longitudinal stripes on the back, typically red, yellow or white.
The snake genus got its common name because people described the stripes as resembling a garter.
Family Elapidae coral snakes (and cobras)
These poisonous snakes have permanently erected fangs.
Coral snake
The only North American member of the cobra family is the coral snake.
Coral snakes are most notable for their red, yellow, and black colored banding. This contrasts to the coral snake mimics, such as the scarlet king snake, which is red, black, and yellow.
Family Crotalidae pit vipers
Most of the poisonous snakes of North America are in this family. All have erectile fangs and loreal pits
—lateral heat sensory organs, between eye and nostril on each side of the head.
Rattlesnake
Notice the rough head scales and the rattle. The loreal pit is very easy to find on this snake.
Water moccasin aka cottonmouth
Notice the smooth head scales.
These snakes are highly venomous and commonly found in the swamps and bayous of the southeastern U.S.
A good climber, the water moccasin often relaxes on branches overhanging the water. If startled it erects its head and shows the white interior of its mouth —hence the name cottonmouth.
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Copperhead
Mature copperheads have a coppery colored head and neck. The copperhead is closely related to the water moccasin and is sometimes called the highland moccasin.
It is venomous but not nearly as venomous as its water moccasin cousin. The striking banding coloration found on these snakes is often described as an hourglass pattern.
Order Crocodilia crocodilians
The crocodilians are large aquatic reptiles with limbs.
Alligator
Alligators are only found in the southeastern U.S. and China!
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They are distinguished from other crocodilians by their broad snout.
SUBCLASS AVES birds
Birds are reptiles that have feathers (which are modified scales), a horny bill, and scales on their feet. Some of the orders of birds familiar to us from our homes, yards, fields, and forests, waterways, and coasts are listed below. Examples of some are on display.
Order
Common name(s)
of birds in Order Examples
Pelecaniformes totipalmate swimmers gannets, cormorants
Ciconiiformes
Anseriformes
Falconiformes
Galliformes
Chicken embryo deep-water waders lamellate-billed swimmers vultures, and diurnal birds of prey gallinaceous birds
(fowl-like) herons, bitterns swans, geese, ducks vultures, eagles, hawks, ospreys, falcons turkeys and chickens
Adult male Galliform birds have a sharp horny spur on the back of each leg, which they use for fighting.
Chickens are evolved from the red jungle fowel of south east Asia.
It was probably first raised in captivity at least 5000 years ago in India.

Charadriiformes
Columbiformes
Psittaciformes
Strigiformes
Apodiformes
Coraciiformes
Piciformes
Passeriformes
Sparrow shore birds and gulls pigeon-like birds parrots, parakeets, macaws nocturnal birds of prey swifts and hummingbirds kingfishers woodpeckers perching or passerine birds
Sparrows are generally small brown-grey birds with short tails and stubby yet powerful beaks. plovers, sandpipers, gulls, terns pigeons, doves owls songbirds
They are predominately seed-eaters but will eat small insects or food left on the street by humans.
CLASS MAMMALIA mammals
Mammals are vertebrates that have mammary glands and hair.
SUBCLASS THERIA
These mammals are viviparous.
INFRACLASS METATHERIA
Mammals with pouches or marsupiums are in this infraclass. All metatherians are in one order.
Order Marsupiala marsupials
Opossum
Notice the pouch.
INFRACLASS EUTHERIA
These viviparous mammals have a true placenta. Representative organisms are on demonstration for several orders.
Order Chiroptera
The word Chiroptera is derived from the Greek meaning “hand-wing.”
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Bat
Most bats are insectivores
(eat insects) or frugivores
(eat fruit).
Order Primates
This group includes lemurs, monkeys (primates with tails) and apes (primates without tails, which of course includes humans).
Humans
If you are very quite you may see one of these elusive creatures.
Order Rodentia
The order Rodentia is the most numerous of all the branches on the mammalian family tree.
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Mice
Like all rodents, mice are herbivorous or scavenging.
They have continuously growing incisors to counteract the wear incurred by the incisors due to constant gnawing.
Order Carnivora
Members of Carnivora have a characteristic skull shape, and their dentition includes prominent canines and carnassial teeth -scissor like molars used to shear meat. The order includes cats, lions, tigers, panthers, dogs, wolves, jackals, bears, raccoons, skunks, and members of the suborder Pinnipedia (sea lions).
Picture of my Dog
He is happy; so no canines are showing!
Order Artiodactyla
All artiodactyls are ungulates (hoofed, grazing animals) that have an even number of toes on each foot
Pig fetus
Be sure you count thenumber of toes for yourself.

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