Echinoderms, Birds, and Mammals
Chapters: 34, 39, 40
I. Diversity- Echinodermata (”Spiny-Skin”)
A. Characteristics
1. undergo metamorphosis from free- swimming larva to bottom dwelling adult. five radii(pentaradial symmetry)
2. endoskeleton, calcium plates, include protruding spines
3. water- vascular system (water- filled canals)
4. tube feet, aid in movement, feeding, respiration, and excretion
5. no circulatory, respiratory or excretory systems
6. nervous system, but no head or brain
7. two sexes, reproduce sexually or asexually
B. Evolution and Classification
1. 500 million years ago in Cambrian period
2. 6,000 species into five classes
a. Crinoidea (”Lily- Like”)
(1) sessile, long stalk attached to sea bottom or rock
(2) mouth doesn’t face sea bottom
(3) five arms divide into more arms, up to 200 in some feather- star species
(4) sticky tube feet, at end of each arm, capture food and respire
b. Asteroidea (”Star- Like”)
(1) sea stars, starfish
(2) prey on oysters, clams, other organisms used as food for humans
c. Ophiuroidea (”Snake- Like”)
(1) basket stars and brittle stars
(2) largest echinoderm Class
(3) long narrow arms, move quickly
(4) feed by raking in food with arms, tube feet, trapping food with tube feet or mucus between spines
d. Echinoidea (”Hedgehog- like”)
(1) endoskeleton called test
(2) grind food with jaw- like Aristotle’s Lantern
(3) tube feet for motion, teeth- like structures for feeding
(4) venom for protection
e. Holothuroidea
(1) armless sea cucumbers
(2) soft body, tube feet on aboral side, tentacles (modified tube feet) surround mouth and sweep in food
(3) when threatened, eject internal organs through anus (evisceration), later regenerate lost parts
II. Structure and Function (Sea Star)
A. Body plan
1. mouth located on underside of body (oral surface)
2. top of body called aboral surface
3. has endoskeleton (within body)
4. ossicle – protective spines on aboral surface, form from calcium plates
5. pedicellariae – surround spines protect and clean surface of body
B. Water- Vascular System
1. used for movement, network of canals, muscle contractions create hydrostatic pressure which permits movement
2. water enters sieve plate, passes through madreporite and down the stone canal, to ring canal and into radial canals, to tube feet, to ampulla
3. allows star fish to climb slippery rocks or catch prey
C. Feeding and Digestion
1. tube feet to obtain food, usually mollusk, worms, and other slow moving animals
2. attaches tube feet to each side of clam shell, and pulls until shell opens
3. turns stomach inside out and inserts stomach into clam
4. enzymes digest clam while still in shell
5. star fish withdraws stomach and digestion is completed
D. Other Body Systems
1. no circulatory, excretory or respiratory systems
2. fluid in coelom bathes organs and provide oxygen
3. gas exchange and excretion from tube feet and skin gills
4. no head or brain, nerve ring surrounds mouth and branches off into Nerve cords that extend into each arm
5. each arm has eyespot that responds to light and tentacle that responds to touch, also tube feet respond to touch
E. Reproduction
1. each arm has two gonads, produce eggs in females and sperm in males
2. fertilization is external, female produces 200 million eggs in one Season
3. each fertilized egg develops into a free swimming larva (bipinnaria)
4. after two years larva settles and metamorphosis begins, develops into adult
5. can also produce asexually by regenerating lost parts, new sea star may develop from segment of arm as long as some of central disk is still attached 34.1
I. Evolution and Classification- vertebrates of the Class Aves
A. Origin and Early Evolution
1. birds evolved from reptiles
2. Archaeopteryx (”ancient wing”), fossils date back to Jurassic period (150 million years ago)
a. evolutionary link between reptiles and birds
b. possesses characteristics of both reptiles and birds
B. Classification
1. about 9,000 species of into 27 orders
2. to classify taxonomists used morphological evidence from beaks, feet, plumage, bone structure, and musculature
II. Characteristics of Birds- body covered with feathers, bones are thin and hollow, their forelimbs function as wings, hind limbs with clawed toes support body, toothless beak present, body temp. regulated internally, 4 chambered heart, eggs (hard, calcium case) incubated in a nest
A. External Characteristics
1. Feathers
a. feathers are modified scales that serve as two primary functions:
(1) providing lift for flight
(2) conserving body heat
b. down feathers cover the body of nesting birds and provide insulation for adults
c. contour feathers give adult birds streamlined shape and provide coloration and more insulation
d. follicles – tiny pits in skin where feathers develop from
e. each vane has many branches called barbs
f. preening- birds use their beaks to rub their feathers with oil secreted by a preen gland, located at the base of the tail.
2. Beaks and Feet
a. hawks and eagles have powerful beaks and clawed talons to capture and rip prey
b. swifts have tiny beaks that open wide to snare insects in midair
B. Internal Characteristics- natural selection has favored a lightweight body, yet the birds powerful wing muscles give it unusual strength
1. Skeleton and Muscles
a. avian skeleton combines strength and lightness with thin and hollow bones
b. furculum (wish- bone) and the sternum (supports breast muscles), unique features of the avian skeleton
c. humerus, ulna, radius, pectoral girdle and the sternum, support the wing
d. flight involves a series of complex wing movements, each using a different set of muscles
2. Endothermy
a. birds are endothermic – they generate and regulate body heat, temperature of a bird ranges from 40 C-42 C
b. with endothermy a bird can inhabit both hot and cold climates
3. Digestive and Excretory Systems
a. food passes from the mouth cavity straight to the esophagus, the crop stores and moistens food, in the first chamber of the two-part stomach, the proventriculus, gastric fluids begin to break down the food, food then passes the gizzard, which kneads and crushes the food
b. excretory system is efficient and lightweight
4. Respiratory System
a. birds require a large amount of oxygen, because of high metabolic rates
b. air enters through paired nostrils near the base of the beak, passes down the trachea past the syrinx and enters the two primary bronchi, moves to lungs
5. Circulatory System
a. birds have a four chambered heart
b. very rapid heartbeat (hummingbird 600 bpm, Chickadee 1,000 bpm)
6. Nervous System
a. birds have large brains, relative to their size
b. the cerebellum coordinates movement and controls complex behavior problems (navigation, mating, nest building, and care of young)
d. poorly developed sense of smell
e. sense of taste helps the birds avoid bitter-tasting or toxic food
7. Reproductive System
a. sperm passes through small tubes called vasa deferentia into the male’s cloaca
b. during mating, the male presses his cloaca to the female’s and releases sperm
c. unfertilized egg contains nucleus, cytoplasm, and a yolk
d. when fertilized, the embryo is suspended in albumen (egg white)
e. the liquid medium supported chalaza that are attached to the shell membrane
III. Development and Behavior
A. Incubation
1. either one or both parents will incubate the eggs by sitting on them and covering them with a thickened, featherless patch of skin on the abdomen (brood patch)
2. embryo development begins when the zygote forms a plate of cells on the surface of the yolk
3. when hatching begins, fully developed embryo makes a star-shaped crack in the shell with the egg tooth on bill
4. birds that lay many eggs and incubate them for a long time hatch precocial young
5. birds that lay few eggs that hatch quickly produce altricial young
B. Behavior
1. Territoriality and Courtship
a. territoriality- male birds establish an area that they defend against other males of their species
b. once a territory is established, birds engage in a period of courtship, designed to attract a mate
2. Nest Building
a. birds construct their nests of almost any material available (twigs, mud, grasses)
3. Migration
a. ornithologists, people who study birds, know that birds rely on a variety of cues to help them navigate.
b. magnetic, changes in air pressure, low- frequency sounds 39.1
I. Evolution and Characteristics
A. Origin
1. evolved from therapsids.
2. fossils found from Mesozoic era.
B. Evolution
1. avoided dinosaurs by being nocturnal
2. didn’t compete with dinosaurs for food by eating insects
3. became dominant in Pateocene epoch
4. Cenozoic era known a Age of Mammals
C. Characteristics
1. endothermic
2. hair
3. four chambered heart
4. diaphragm that aids in breathing
5. single lower jawbone, 4 types teeth-incisors-bite and cut canines-grip, puncture, tear bicuspids-two point molars-grind and crush.
6. viviparous-young inside the females uterus during development and then give birth to live young
7. females secret milk through mammary glands to feed newborn young
8. highly developed brain
D. Classification
1. Differences from other vertebrates
a. hair
b. produce milk to feed young
2. 19 orders of modern mammals in class Mammalia
a. 17 are placental, nourish unborn young via the placenta
b. 2 remaining are egg laying and pouched mammals
II. Monotreme and Marsupials
A. Monotremata
1. Similarities to reptiles
a. oviparious
b. not completely endothermic
c. body temp. lowered and fluctuates more than other mammals
d. everything from large intestine, urinary bladder, and reproductive organs empty into cloaca
B. Marsupialia
1. give birth to tiny young that live in pouch of the female
2. dominant in Australia
a. when Australia broke off from the larger landmass no placental mammals inhabited the continent
b. on other continent the placental mammals out competed the marsupials and they became instinct.
III. Placental Mammals
A. Characteristics
1. carry young in uterus until born, nourished by placenta, an organ formed from the chorion and allantois
2. period of time when developing in uterus is called gestation period
B. Classification
1. Insectivora- 400 species
a. long pointed noses
b. teeth adapted to picking up and piercing their prey
c. adapted to life on ground, trees, water, and underground.
2. Rodentia- 2400 species
a. largest mammalian order
b. 2 incisors in each jaw, adapted for harsh food
3. Lagomorpha- 70 species
a. double row of upper incisors
b. herbivores
4. Edentata- 30 species
a. ant eaters no teeth, rest some teeth
b. insectivorous diet
c. long sticky tongue, long clawed front paws
5. Chriroptera- 900 species
a. only true flyers
b. live world wide except polar environments
c. nocturnal
d. echolocation to find food and to navigate, emit high- frequency sound waves
e. feed on insects, fruit and flower nectar
6. Cetacea- 90 species
a. breathe through a blowhole
b. two groups of whales
(1) toothed whales
(2) baleen whales
7. Sirenia- 4 species
a. manatees and dugongs
b. herbivores
8. Carnivora- 250 species
a. most are carnivores hence the order name
b. bears and other members are omnivorous
9. Pinnipedia- 34 species
a. water dwelling carnivores
b. adapted for efficient swimming
10. Artiodactyla and Perssodactyla- 165 species
a. ungulates (hoofed mammals), with even number of toes belong to Artiodactyla, odd number of toes make up Perissodactyla
b. both orders are herbivores
11. Proboscidea- 2 species
a. boneless trunked nose or proboscis
b. largest land dwellers today
12. Primates- 200 species
a. most are omnivorous, and have teeth designed for a varied diet
b. complex brain