AD CH 14, 15, 16, 17

Phylum Echinodermata Classes

Asteroidea, Ophiuroidea, Echinoidea, Holothuroidea, Crinoidea

Phylum in Clade Ambulacraria

Echinodermata and Hemichordata

Phyla Echinodermata and Phyla Hemichordata sister taxa

chordata

Phylum Echinodermata General Characteristics

1. All are marine
2. Calcareous, Spiny endoskeleton of plates or ossicles
3. Pedicellariae
4. Unique water-vascular system
5. Pentaradial symmetry in adults
6. Larvae are bilateral (bilateral ancestry)
7. Lack ability to osmoregulate: marine only
8. Embryonic coelom divided into 3 coelomic
cavities (tripartite)
9. Mostly mobile predators or herbivores
10. Important molders of many ecosystems (kelp forest, coral reef)

Class Asteroidea Aboral Side

Arms, anus, central disc, madreporite

Class Asteroidea Oral Side

Mouth, arms, spine, tube feet, ambulacral grooves, sensory tentacles

Class Asteroidea (sea stars) External Structure

a. Have a central disc with 5 tapering arms extending outward
b. Mouth is on the oral surface, aboral surface is opposite
c. Ambulacral groove bordered by rows of tube feet along oral surface of each ray
d. Radial nerve located in center of each ambulacral groove (oral to radial canal)
e. Under the nerve is an extension of the coelom and the radial canal of the water- vascular system (aboral to nerve)
f. Aboral surface is spiny
g. At base of spines are groups of pincer-like
pedicellariae
h. Papulae (or skin gills) are soft ciliated
projections continuous with 1st coelom (respiration)
i. Madreporite: aboral Sieve leading to the water- vascular system via the stone canal

Class Asteroidea (sea stars) Internal Structure

a. Under the epidermis is the Mesodermal endoskeleton made of small calcareous plates or ossicles bound together with CT (can mutate btw liquid and solid)
b. Body Coelom (1st coelomic division)
-1st coelomic division
-Ciliated peritoneal lining of coelom circulates
fluid around the cavity and into
papulae
-Respiratory gases and ammonia diffuse across the papulae and tube feet
c. Water-Vascular System (2nd coelomic division)
-Opens to outside at madreporite on aboral side
-Madreporite joins to stone canal which then joins to the ring canal that encircles the mouth and extends into radial canals
-ampulla and tube foot attached to radial canal
-coelomic compartment unique to echinoderms
-Consists of system of canals, tube feet, and dermal ossicles
-Functions in locomotion, sensory, food-gathering, respiration, and excretion
-Outer end of each tube foot bears a sucker
-Water-vascular system operates hydraulically
-Valves in lateral canals prevent backflow
-Muscles in ampulla and tube feet contract forcing fluid to extend the podium, move rays, create suction
d. Feeding and Digestive System
- Mouth leads to two-part stomach located in the central disc
- Large lower cardiac part of stomach can
be everted through the mouth during feeding
- Upper stomach is smaller and connected by ducts to paired pyloric ceca (digestive glands) in each arm
- Consume a wide range of food
- Molluscs are faves- starfish inserts its soft everted stomach into crack of bivalve shell

Class Asteroidea (sea stars) Nervous System

- oral system of a nerve ring and radial nerves
coordinate the tube feet: no brain or central
ganglion
- Epidermal nerve plexus connects the radial
systems of nerves (allow communication
between legs)
- Sense organs include an eyespot at the
tip of each arm
- Sensory cells scattered over the epidermis
(touch, chemical)

Class Asteroidea (sea stars) Reproductive System/Regeneration/Autonomy

- Sexes separate in most species (external fert.) - Pair of gonads in each interradial space
- Regenerate lost parts
- Cast off injured arms and regenerate new ones
-An arm can regenerate a new sea star if at least one-fifth of central disc is present
-Free-swimming larva are bilateral then
metamorphosizes to benthic pentaradial juveniles

Regeneration is a form of

asexual reproduction

Class Ophiuroidea (brittle stars) General

a. Arms of brittle stars are slender and distinct from the central disc
b. Lack pedicellariae or papulae
c. Tube feet lack suckers
d. Madreporite is on the oral surface
e. Locomotion is by arm movement
f. Five movable plates act as jaws and surround mouth
g. No anus or intestine.... you guessed it, they poop out their mouth
h. Skin is leathery and surface cilia are mostly lacking
i. Visceral organs are in the central disc
j. Larvae has ciliated bands that extend onto delicate and beautiful larval arms
k. Brittle stars are secretive and Often live under rocks
l. Regeneration more pronounced than in sea stars
m. Very fragile (they can easily regenerate) (brittle)

Class Echinoidea (sea urchins, sand dollars, and Heart Urchins)

a. Sea urchins lack arms but their tests (shell) show five- part symmetry
b. hemispherical shape with radial symmetry and long spines
c. Sand dollars and heart urchins (irregular echinoids) have become bilateral (shift of mouth and anus) w short spines
d. Regular urchins move by tube feet
e. Irregular urchins move by their spines
f. Echinoids occur from intertidal regions to deep ocean
g. Echinoid test has ten double rows of plates with movable, stiff spines (muscles at base) (fused ossicles)
h. Tube feet extend along the 5 ambulacral rows
i. Some species have pedicellariae with venomous glands that secrete a toxin that paralyzes small prey. However, most graze
j. Inside the test is Aristotle's lantern(chewing structures )

Class Holothuroidea (sea cucumbers) General

a. As common name suggests, they resemble cucumbers
b. Greatly elongated in the oral- aboral axis (not cephalized)
c. Ossicles are greatly reduced and body wall is leathery
d. Some species crawl on the ocean bottom, others are found under rocks or burrow
e. Tube feet on dorsal side are reduced and may serve a sensory role
f. Sea cucumbers use ventral tube feet & muscular body waves to move
g. Secondarily bilateral (not cephalized)
h. Oral tentacles are 10-30 tube feet surrounding the mouth
i. Coelomic cavity serves as hydrostatic skeleton
j. Respiratory tree empties into cloaca
k. Respiratory tree also serves for excretion
l. Gas exchange also occurs through the skin and tube feet
m. Sea cucumbers have a single gonad (only echinoderm)
n. can trap particles on tentacle mucus, ingesting food into pharynx
o. Others graze sea bottom with tentacles
p. Cuvierian tubules are expelled in direction of an enemy
- Sticky and have toxins and can entangle prey
- Some species also discharge the digestive tract, respiratory tree, or gonads
- All of these structures can be regenerated

Class Crinoidea (sea lilies and feather stars) General

a. numerous in fossil record
b. Sea lilies are attached for most of their life
c. Sea lilies have a flower-shaped body at tip of a stalk
d. Feather stars have long, many-branched arms
e. Many crinoids are deep-water species
f. Feather stars are found in more shallow water
g. covered with a leathery skin of calcareous plates
h. The 5 arms branch to form more arms/feathers
i. Madreporite, spines, and pedicellariae are absent
j. Tube feet and mucous strands allow it to feed on small organisms and transfer them to the ambulacral grooves
k. Has a water-vascular system

Echinoderm Phylogeny

1. From the larvae, we know the ancestor was bilateral and the coelom had three pairs of spaces
2. If ancestors had a brain and sense organs, these were lost in adoption of radial symmetry
3. Current evidence suggests that the oral surface is anterior and the aboral surface is posterior
4. The arms represent lateral growth zones
5. Basic body plan has limited evolutionary opportunities to become parasites (no echinoderms are parasites)

Echinoderm Adaptive Diversification

Current genetic research is trying to identify anterioposterior axis of adult echinoderms

Success of group as benthic filter-feeders, deposit- feeders, suspension feeders, scavengers, and herbivores

Phylum Hemichordata (acorn worms) Characteristics

1. Formerly considered a subphylum of chordates based on presence of gill slits and a rudimentary notochord
2. The "notochord" is really an evagination of the mouth cavity
3. Wormlike bottom dwellers, living in shallow waters
4. Active proboscis collects food in mucous strands
5. Have a ventral nerve cord and a larger dorsal
nerve cord that is hollow in some species (chordate-ish)
6. Sexes are separate Fertilization is external

Phylum Hemichordata (acorn worms) Phylogeny

1. Phylogenyfarfrom
being completely understood
2. Share characters with both echinoderms and Chordates Pharnygeal slits (chordates)

Phyla of Deuterostomes

Echinodermata, Hemichordata, Chordata

Chordate Evolution and Classification

-Name Chordata comes from the notochord
-Notochord is a hydrostatic organ Supportive, cartilaginous rod in all chordates
-Chordates share features with some invertebrates:
1. Bilateral symmetry
2. Anterioposterior axis
3. Coelom: Tube-within-a-tube body plan
4. Metamerism (segmentation)
5. Cephalization
-Chordates are deuterostomes therefore share features with Echinodermata and Hemichordata
1. Conditional specification
2. Radial embryonic cleavage
3. Regulative development
4. Anus from blastopore

Traditional and Cladistic Classification of the chordates

1. turtles, lizards, snakes, crocodiles, birds and mammals compose a monophyletic clade called Amniota
2. "Reptiles" can only be grouped as amniotes that are not birds or mammals
3. No derived characters that group only reptiles to the exclusion of birds and mammals

Chordates Ancestry and Evolution

1. Deuterostomes arose in the Precambrian seas
2. Chordates first appeared in the Cambrian period (540MYA)
3. Chordata divided into 3 subphyla: Urochordata (tunicates)
Cephalochordata (lancelet or Amphioxus) Vertebrata
4. Urochordata and Cephalochordata form the Protochordata clade

Five Chordate characteristics

A. Dorsal, tubular nerve cord
B. Notochord
C. Pharyngeal slits
D. Endostyle or thyroid gland
E. Postanal tail

Chordates: Dorsal, tubular nerve cord

1. In comparison, most invertebrate phyla had a solid nerve cord that was ventral to digestive tract
2. In chordates, Single, tubular nerve cord is dorsal to digestive tract
3. Nerve cord is anterior and enlarges to form the brain (cephalization). Cord is hollow
4. Cord is produced in embryo by enfolding of ectodermal cells on the dorsal side of body-Neural crest cells and migration only in vertebrates

Chordates: Notocord

1. Always found at some embryonic stage
2. First part of the endoskeleton to appear in the embryo
3. Rodlike, semirigid, extends the length of body just ventral to the central nervous system
4. Supports and stiffens body, providing skeletal Scaffolding for the attachment of muscles
5. Can bend without shortening and permits undulation

Chordates: Pharyngeal Pouches and Slits

1. Pouches form by the in invagination (inpocketing) of ectoderm and the evagination (outpocketing) of endoderm of the pharynx
2. Pouches perforate pharynx in Protochordates and serve as a filter-feeding apparatus
3. Addition of capillary network and thin gas-permeable walls led to evolution of internal gills
4. In Tetrapods: Pharyngeal pouches give rise to a variety of structures including: Eustachian tube, middle ear cavity, larynx, tonsils, jaw structures and parathyroid glands
5. ALWAYS serves a function of separating food from oxygen (pharyngeal feeding slits, gills, larynx/pharynx) ***KEY POINT IN EVOLUTION**

Chordates: Endostyle or Thyroid Gland

1. Recently, the endostyle was recognized as a shared chordate character
2. Endostyle or its derivative, the thyroid gland, found in all chordates
3. Some cells in endostyle secrete iodinated proteins homologous with the iodinated-hormonesecreting thyroid gland of adult lampreys and all other vertebrates

Chordate: Postanal tail

1. Postanal tail, plus musculature, provided motility for larval tunicates and Amphioxus to swim.
2. Increases swimming efficiency in fishes but became smaller or vestigial in some later lineages (human coccyx)

subphyla in Phylum Chordata

1. Subphylum Urochordata (tunicates)
2. Subphylum Cephalochordata (lancelet: Amphioxus)
3. Subphylum Vertebrata

What subphyla in Phylum Chordata are protochordates?

1. Subphylum Urochordata (tunicates)
2. Subphylum Cephalochordata (lancelet: Amphioxus)

Subphylum Urochordata: Tunicates "tail-chordates": Diversity

1. Occur in all seas/depths
2. Most are sessile as adults
3. tunic is touch, non-living test that surrounds them
4. In most, only the larval form bears all 5 chordate hallmarks
5. During adult metamorphosis
a. Notochord and tail disappear
b. Dorsal nerve cord is reduced to a single ganglion

Subphylum Urochordata: Tunicates "tail-chordates" Representatives

Tunicates

Subphylum Urochordata: Tunicates "tail-chordates": Representative Tunicates General

1. called sea squirts because they discharge a jet of water when disturbed
2. Water entering the incurrent siphon passes through a pharynx through gill slits and then out through the excurrent siphon
3. Feeding depends on the formation of a mucous net that is secreted by the ciliated endostyle
4. Particles trapped in pharynx are worked into a rope and carried back to the esophagus and stomach
5. Heart drives blood first in one direction, then in reverse
6. Hermaphroditic with external fertilization
7. Tadpole larvae Have all 5 chordate characteristics

Subphylum Cephalochordata (lancelets = Amphioxus): General Characteristic

1. Slender, laterally flattened, translucent animals about 3-7 cm long
2. Live in sandy bottoms of coastal waters
3. Amphioxus (lancelets) possess the five distinctive characteristics of all chordates

Subphylum Cephalochordata (lancelets = Amphioxus): Digestive System

1. Water enters the mouth driven by cilia passes through pharyngeal slits where food is trapped in mucus secreted by the endostyle
2. Food moved via cilia to gut then hepatic ceca, where particles are phagocytized & digested intracellularly
3. Water exits through an atriopore (equivalent to excurrent siphon of tunicates)

Subphylum Cephalochordata (lancelets = Amphioxus): Circulatory system

1. Closed circulatory system is complex but lacks a heart
2. Blood lacks erythrocytes and hemoglobin and mainly circulates nutrients (gases exchanged mainly across atrium)

Subphylum Cephalochordata (lancelets = Amphioxus): Nervous System

1. Hollow nerve cord lies above the notochord
2. Sense organs are simple, including an unpaired ocellus that functions as a photoreceptor
3. Anterior nerve cord is not enlarged significantly (despite name of subphylum)

Subphylum Cephalochordata (lancelets = Amphioxus): Reproduction system

1. Sexes are separate (dioecious)
2. Fertilization is external
3. Larvae soon hatch and gradually assume the shape of adults

Subphylum Cephalochordata (lancelets = Amphioxus): Basic Plan

1. possesses features that suggest the vertebrate plan
2. Hepatic cecum is a diverticulum which secretes digestive enzymes
3. Segmented trunk musculature (metameric somites)
4. Possess basic circulatory pattern of more advanced chordates

Subphylum Vertebrata: General Info

-Share the five diagnostic chordate characteristics BUT has novel characters not found in Cephalochordata or Urochordata
-Vertebrates have several clusters of HOX genes... this indicates duplication of positional genes that control body plan and therefore allow for increased complexity of the subphylum Vertebrata
-Some of the diagnostic chordate characteristics are modified into these novel characters: jaws, paired appendages, vertebrae, etc

Modifications of the basic Chordate plan in subphylum Vertebrata

A. Musculoskeletal Modifications
B. Physiology Upgrades
C. New Head, Brain, and Sensory Systems
D. Neural Crest, Ectodermal Placodes, & Hox Genes

Subphylum Vertebrata: Musculoskeletal Modifications in Vertebrates

1. Structural strength of bone is superior to cartilage for muscle attachment in areas of high mechanical stress (endoskeleton)
2. Earliest fishes, including Ostracoderms and placoderms were partly covered in bony, dermal armor: Modified in later fishes as scales
3. Most vertebrates are protected with keratinized structures derived from the epidermis (Reptilian scales, hair, feathers, claws, and horns)

Subphylum Vertebrata: Physiology Upgrade

1. Digestive, respiratory, circulatory, and excretory systems modified to meet increased metabolic demand
2. To manage increased ingestion of food:
a. Gut shifted from movement of food by ciliary action to muscular action
b. Accessory digestive glands, the liver and pancreas, produce secretions that aid digestion
3. Transportation of nutrients gases, & other substances enhanced by
a. Ventral chambered heart
b. Erythrocytes containing hemoglobin
c. Muscular pharynx to move water
4. Vertebrates possess paired, glomerular kidneys to remove metabolic waste products and regulate body fluid composition
5. Shift from filter feeding to active predation required new sensory, motor, and integrative controls for locating and capturing larger prey

Subphylum Vertebrata: New Head, Brain, and Sensory Systems

1. Anterior end of nerve cord enlarged as a tripartite brain:
a. Forebrain, midbrain, and hindbrain
b. Brain protected by cartilaginous or bony cranium
2. Paired special sense organs for vision, equilibrium, and sound evolved
3. Chemical receptors, including taste & exquisitely sensitive olfactory organs; lateral line receptors for detecting water vibrations; and electroreceptor for detecting prey

Subphylum Vertebrata: Neural Crest, Ectodermal Placodes, & Hox Genes

-two embryonic innovations unique to vertebrates: Neural crest Ectodermal placodes

Subphylum Vertebrata: Neutral Crest

Neural crest:
a. Derived from ectodermal cells along embryonic neural tube
b. Contributes to formation of :
i. Most of the cranium
ii. pharyngeal skeleton
iii. tooth dentine
iv. Schwann cells
v. some endocrine glands

only in vertebrates

Subphylum Vertebrata: Ectodermal placodes

Ectodermal placodes
a. Plate-like ectodermal thickenings on either side of neural tube
b. Give rise to:
i. olfactory epithelium
ii. lens of eye
iii. inner ear epithelium
iv. some ganglia and cranial nerves
v. lateral-line mechanoreceptors & electroreceptors

Subphylum Vertebrata: Hox Genes

Hox Genes (genes that control embryonic development along anterior/posterior axis):
a. One cluster of Hox genes is found in Amphioxus and other invertebrates (ex: 1 cluster of 8 hox genes in Hexapoda)
b. All living gnathostomes have 4+ clusters (Chondrichthyes, bony fishes, and Tetrapods)

Subphylum Vertebrate: Chordate Evolution and the Position of Amphioxus

1. Cephalochordata is a sister group to (Urochordata and Vertebrata combined)
2. Urochordates (tunicates) are considered the closest living relatives of the vertebrates
-Common ancestor would be a fee-swimming chordate
3. Amphioxus is unlikely the most recent common ancestor of vertebrates a. Lancelet (Amphioxus) lacks:
i. Tripartite brain
ii. Chambered heart
iii. Special sensory organs
iv. Muscular gut and pharynx
v. Neural crest tissue inferred to have been present in ancestor

Subphylum Vertebrate: The Earliest Vertebrates

1. Earliest known vertebrates were small, soft-bodied forms from the Cambrian (530-500 MYA)- Early chordate with several vertebrate features (Cambrian shales of China) MAYBE extinct sister to vertebrates
2. Ostracoderms (not monophyletic) (440-360 MYA)
a. Armored jawless fishes
b. Strong pharyngeal muscles to pull in prey- used strong pharyngeal pump instead of cilia to move food

Subphylum Vertebrata: Early Jawed Vertebrates

1. Gnathostomes (jaw mouth)
a. Include all living and extinct jawed vertebrates
b. Constitute a monophyletic group
c. Presence of jaws is a derived character shared by all jawed fishes & Tetrapods
2. Evidence indicates jaws arose by modification of 1st two cartilaginous gill arches
3. Paired fins may have risen from paired continuous, ventrolateral folds or forming zones.
4. Addition of skeleton supports within the fins provided stability during swimming

Sister to Gnathostomes

Agnatha (no jaw)

Subphylum Vertebrata: Living Fishes

1. Gnathostomata (jawed mouth) and Agnatha (without jaws) clades comprise the subphylum vertebrata
2. Agnatha includes hagfishes and lampreys
3. Gnathostomata includes Chondrichthyes and Osteichthyes
4. Osteichthyes includes the bony fishes and Tetrapods

What is a Fish?

A. Fish do NOT form a monophyletic group, they are just vertebrates that are not Tetrapods
B. There are as many fish species as all other species of vertebrates combined
C. Cladistic approach puts jawless fish in the clade Cylcostomata and the jawed fish with the tetrapods in the clade Gnathostomata
-All living fishes are either Cyclostamata or Gnathostomata which includes finned fish with paired appendages and Tetrapods as a monophyletic clade: Gnatha=jaw stome=mouth

Ancestry & Relationships of Major Groups of Fishes

-Fishes are gill-breathing, aquatic vertebrates with fins
-Fish are just vertebrates that are not Tetrapods

Five major groups of living fishes

1. Hagfishes
2. Lampreys
3. Cartilaginous fishes
4. Ray-finned fishes
5. Lob-finned fishes
6. Tetrapods (not a main group-not fish)

Cyclostomata groups

1. Hagfishes
2. Lampreys

Chondrichthyes Groups

3. Cartilaginous fishes

Osteichthyes groups

4. Ray-finned fishes
5. Lob-finned fishes
6. Tetrapods (not a main group-not fish)

Gnathostomata groups

3. Cartilaginous fishes
4. Ray-finned fishes
5. Lob-finned fishes
6. Tetrapods (not a main group-not fish)

Living Jawless Fishes: Cyclostomata

A. lampreys and hagfish will be considered together as representatives of Cyclostomata
B. They share:
1. lack of jaws
2. No paired fins and are scaleless
3. Pore-like gill openings
4. Eel-like body plan
5. Persistent notochord
C. Hagfish
1. Have secondarily lost vertebral column (skull still present) 2. Can bore into prey
3. Blind, but have a keen sense of smell and touch
4. Slime kings
D. Lampreys
1. About half are parasitic as adults, the other half doesn't feed after metamorphosis
2. Filter feed as larvae (3-7 years) in freshwater

Cartilaginous Fishes: Chondrichthyes

A. Class Chondrichthyes is a clade of its own
B. Contains sharks, skates, rays, and ratfish
C. Characteristics
1. Cartilaginous skeleton
2. Jaws with polyphyodont teeth
3. Placoid scales or naked
4. Spiral valve within intestines
5. No swim bladder
6. Internal fertilization (claspers)
D. Class Chondrichthyes divided into 2 clades (subclasses): Elasmobranchii (sharks, skates, and rays)
Chimaeras (ratfish) (we won't cover)

Cartilaginous Fishes: Chondrichthyes: Sharks, Skates and Rays: ELASMOBRANCHII

1. Sharks are heavier than water: when awake, must always move (they use ram ventilation)
2. gill slits and gills with a spiracle behind each eye
3. Heterocercal tail (vertebrate is IN tail)
4. Well developed lateral line (detect vibrations)
5. Electroreceptors in the ampullae of Lorenzini
6. Details of characteristics
a. Spiracle: Spiracle is remnant of proximal gill arch. Delivers oxygen to eye/brain
b. Teeth: develop inside jaw and rotate out (critical in rays and skates) Polyphyodont dentition
c. Lateral Line: neuromasts in interconnected tubes and pores on side
d. Ampullae of Lorenzini: electroreceptors in gel around head
e. Spiral valve: increases SA of intestine but limits passage
f. Clasper: modified pelvic fin used in copulation
7. Maternal support of embryo is variable
a. oviparous (egg cases skates and rays)
b. ovoviviparous
c. viviparous
8. Rays
a. Dorsoventrally flattened with enlarged pectoral fins ("fly" through water)
b. Respiratory: water enters through large spiracles (gills underneath)
c. teeth crush prey: molluscs, crustaceans, and small fish

Subphylum Vertebrata Clades

Class Cyclostomata and infraphylum Gnathostomata

Bony Fishes and Tetrapods: OSTEICHTHYES: Origin, Evolution, and Diversity

1. clade contains 95% of all living fish & tetrapods
2. All Osteichthyes have:
a. Endochondral bone that replaces cartilage during development
b. Lung or swim bladder is present (from gut) never both!!!
c. Operculum over the gills (bony fish)
d. muscular and skeletal elements aid in suction feeding
3. Osteichthyes includes bony fish and Tetrapods
4. Bony fish are merely Osteichthyes that don't have limbs
5. Bony fishes are divided into 2 major clades:
-Ray-finned fishes (Teleosts and a few odd balls; gars, paddlefish...)
-Lobe-finned fishes (coelacanth and lungfishes)
6. Bony fish characteristics (Teleosts and lobe-finned fishes) a. Operculum increases respiratory efficiency (increased O2 demand)
b. All have a gas-filled structure off the esophagus
-Structure can be lung if used for respiration Structure can be swim bladder if used for buoyancy

Clades of boney fishes

Ray-finned fishes (Teleosts and a few odd balls; gars, paddlefish...)
Lobe-finned fishes (coelacanth and lungfishes)

Bony Fishes and Tetrapods: OSTEICHTHYE: Ray-Finned Fishes: (Actinopterygii)

1. Variable scale types: Placoid, ganoid, cycloid or ctenoid
2. Caudal fins are homocercal in ray-finned fishes, in some other bony fishes they are Diphycercal (lungfish(a lobe-finned fish))
3. Teleosts (includes most ray-finned fishes)
a. 95% of all living fishes
b. Inhabit nearly every aquatic habitat ... even land (mudskipper who holds water over gills)
c. scales are in dermis and covered by epidermis (cycloid or ctenoid) they grow with fish (rings)
4. Homocercal tail
5. Specialization of jaw musculature improves feeding(Negative pressure "sucks in" prey)

Bony Fishes and Tetrapods: OSTEICHTHYE: LOBE-FINNED FISHES (lungfishes and coelocanths)

1. lung fish have lungs instead of swimbladders
2. Coelocanthes are not a missing evolutionary link

Structural and Functional Adaptations of Fishes: Locomotion in Water

1. Speed
a. Most fishes swim maximally at ten body lengths per second (minnow...not so fast) Larger fish therefore swims faster
b. Short bursts of speed are possible for a few
2. Mechanism
a. Trunk and tail musculature propels a fish
b. Muscles are arranged in zigzag bands: myomeres

Structural and Functional Adaptations of Fishes: Neutral Buoyancy and the Swim Bladder

1. Fish are slightly heavier than water
2. Sharks continually move forward to avoid sinking Fins keep it "angled up"
3. Shark liver has a special lipid, that acts to keep the shark a little buoyant
4. Swim bladder in bony fish, as a gas-filled space, is the most efficient flotation device
5. Absent in tunas, some abyssal fishes, and most bottom dwellers
6. Fish controls depth by adjusting volume of gas in swim bladder
7. Gas is secreted into the bladder from the blood via the gas gland
8. This gland uses a network of capillaries, rete mirabile, a countercurrent exchange system, to trap gases
9. The rete allows oxygen to reach high concentrations in the gas gland, permitting it to diffuse into the swim bladder

LUNG AND SWIM BLADDER: Homologous structures

-Both derived from gut NOT PHARYNGEAL ARCHES
-Pharyngeal pouches/slits become fish = gills/jaw
-Tetrapods = jaw/pharynx/larynx
-NO ANIMAL HAS SWIM BLADDER & LUNG

Structural and Functional Adaptations of Fishes: Respiration

1. Fish gills are thin filaments with thin epidermal membranes folded into plate-like lamellae
2. Gills are inside the pharyngeal cavity and covered with a movable flap, the operculum
3. Operculum protects delicate gill filaments and streamlines body
4. Pumping action by operculum helps move water through the mouth, across the gills, and out the gill slits
5. Elasmobranchs have a series of gill slits out of which the water flows
6. water flow over gills is continuous
7. Water flow is opposite to the blood flow -Countercurrent flow maximizes exchange of gases
8. Some bony fishes remove 85% of the oxygen from water passing over gills (yet another great counter current exchange system)
9. Some active fishes use ram ventilation
-Forward movement is sufficient to force water across gills
-Such fishes are asphyxiated in a restrictive aquarium even if the water is saturated with oxygen (mackerel (tuna family), sharks)

Structural and Functional Adaptations of Fishes: Osmotic Regulation

1. Freshwater is hypotonic to fish blood
a. Water enters body and salt is lost by diffusion
b. Scaled and mucous-covered body is mostly impermeable, but gills allow water and salt fluxes
2. Freshwater fishes are hyperosmotic regulators
a. kidney pumps excess water out
b. Special salt-absorbing cells located in gill epithelium actively move salt ions from water into fishes' blood to replace diffusive salt loss
c. Systems are efficient Freshwater fish spend little energy maintaining osmotic balance
3. Marine bony fishes are hypoosmotic regulators
a. Blood is hypotonic to seawater
b. Tend to lose water and gain salt
c. Risks "drying out"
d. To compensate for water loss, a marine teleost drinks seawater
e. Brings in more unneeded salt which is carried by blood to gills and secreted by special salt- secretory cells
f. Divalent ions of magnesium, sulfate and calcium are left in intestine and leave body with the feces

As you study the internal anatomy of a sea star, your lab partner notes the presence of calcareous plates underneath the epidermis. She believes these are an anomaly. You explain to her that these are

ossicles

Why would taxonomists think that vertebrate animals (such as mammals) are more closely related to a sea star than an octopus? After all, the octopus has a brain, well-developed eyes and other attributes that seem more like vertebrates.

The reason stems from early embryological development patterns that sea star and vertebrates have in common.

The complex chewing apparatus found in sea urchins is the

Aristotle's lantern

The gill slits of enteropneust hemichordates function to

allow water to exit after food has been gathered from the inflow.

in order to describe the difference between Holothuroidea body form and structure vs that if a typical echinoderm place the descriptive terms in the appropriate boxes

Echinoderm- Pentaradial body shape, Ossicles large; determine the body shape, Presence of arms or spines and Primary movement using tube feet.

Holothuroidea- Oblong tubular body, Respiratory tree, Ossicles microscopic and Oral tube feet and feeding.

Write the name for animals in phyla echinodermata, hemichordata, and chordata where the fertilized egg develops an any day the location of the opening of the embryo known as the blastopore.

deuterostome

which one of the following groups always possess all five hallmarks chordate characteristics as adults

cephalochordata

How do we know that echinoderms were derived from an ancestor with bilateral symmetry?

Echinoderms have bilaterally symmetrical larva

FRESHWATER FISH:

drink little, pee tons, have large kidney

MARINE FISH:

Drink a ton, pee little (highly concentrated), have wimpy kidneys

Structural and Functional Adaptations of Fishes: Reproduction and Growth

1. Most fishes are dioecious with external fertilization and external development
-Compare oviparity, ovoviviparity, and viviparity
2. Guppies and mollies represent ovoviviparous fish that develop in ovarian cavity
3. Some sharks are viviparous with some kind of placental attachment to nourish young
4. Most oviparous pelagic fish lay huge numbers of eggs
-Some bury eggs
-Many attach eggs to vegetation
-Some incubate eggs in their mouth
4. Most oviparous pelagic fish lay huge numbers of eggs
-Some even hold fry in mouth (mouth brooding)
5. Many benthic spawners guard eggs
- Male is usually the guard
6. Fishes may have elaborate courtship displays
7. Fish eggs hatch and then the fry carry a yolk sac to supply food until it can forage

Structural and Functional Adaptations of Fishes: Migration

Homing Salmon
1. Salmon are anadromous Grow up in sea but return to freshwater to spawn
2. 6 species of Pacific salmon and 1 Atlantic salmon migrate 3. Atlantic salmon makes repeated spawning runs
4. Pacific species spawn once and die
5.Pacific species of sockeye salmon
a. Fry migrates downstream
b. Roams the Pacific for 4 years
c. Returns to spawn in headwaters of parents' stream
d. Young fish are imprinted on odor of their stream
e. May navigate to stream mouth by sensing magnetic field of the earth or angle of the sun, and then smelling their way home
6. Salmon are endangered by stream degradation from logging, pollution and hydroelectric dams

From Water to Land in Ontogeny and Pylogeny

Amphibians transition from water to land in ontogeny and phylogeny
Air has 20 x O2 levels, but air is far less supportive and has a lower inertia for heat compared to water
Easier to get oxygen but Need: stronger skeleton
Ability to tolerate
Temperature swings