Bio 2 Exam 3

Tissues

Groups of similar cells that act as functional unit

Cleavage

Animal zygotes undergo, zygote divides very rapidly, without growth between divisions

Blastula

Hollow ball of cells, cleavage leads to this formation

Gastrulation

Blastula will undergo, forming Gastrula with different layers of embryonic tissues

Larva

Sexually immature & morphologically & behaviorally distinct from adult stage

Metamorphosis

Larvae becomes juveniles, resembles adults but sexually immature

Embryos regulate these genes to be able to develop into adults

Animals share unique regulatory genes Hox genes, control expression of many other genes

Body plans

Sets if morphological & developmental traits

Radial symmetry

Body parts arranged around single central axis

Imaginary slice that divides animal into mirroring images

Bilateral Symmetry

Body parts arranged around 2 axes of orientation, head-tail axis & dorsal-ventral axis

Imaginary slice divides into mirror-image halves right & left sides

Ectoderm

Covers embryos’ surface, gives rise to outer covering & central nervous system

Endoderm

Innermost layer, lines blind pouch (archenteron) form the gut, gives rise to lining of digestive tract & organs

Diploblastic

Animals, cnidarians, only ectoderm & endoderm

Triploblastic

Animals including all bilaterally symmetrical animals, have 3rd germ layer

Mesoderm

Muscles develop from, fills space between ectoderm & endoderm, gives rise to muscles & most organs

Body cavity

Fluid-/air-filled space between digestive tract & outer body walls

Cavity enables internal organs to grow & move independently of outer body wall

Coelom

Fluid filled body cavity, body cavity surrounded by tissues deprived from mesoderm

Pseudocoelomates

Other triploblastic animals, have Blastocoelom, body cavity formed between mesoderm & endoderm

Spiral Cleavage

Planes of cell division are diagonal to vertical axis of the embryos

Determinate Cleavage

Developmental fate of each embryonic cell is rigidly determined very early

Radial & indeterminate

Radial Cleavage

Planes of division are either parallel/ perpendicular to embryo’s vertical axis

Indeterminate Cleavage

Each cell produced by early cleavage, able to form a complete embryo

Archenteron

(Becomes the gut), during gastrulation embryo forms blind pouch

Protostome splitting of solid masses of mesoderm forms coelom

Deuterostome mesoderm buds from wall of archenteron to form coelom

Blastopore

Indentation in the gastrula that leads to formation of archenteron

Protostome blastopore becomes the mouth

Deuterostome blastopore becomes the anus

5 important relationships among living animals reflected in their phylogeny

1. Animals share a common ancestor

2. Uncertainty about which phylum is sister clade to all others

3. Cnidarians are closely related to bilaterians

4. Most animal phyla belongs to clade Bilateria

5. 3 major clades of Bilateria animals: Deuterostomia, Lophotrochozoa, & Ecdysozoa

Invertebrates

All phyla, animals that lack a backbone, except phylum chordata of clade deuterostomia

Vertebrates

Animals with a backbone,includes phylum chordata of clade deuterostomia

Deuterostomia

Clade, are deuterostomes, hemichordates (acorn worms), echinoderms (sea stars & relatives), & chordates (include vertebrates)

Ecdysozoa

Secrete an external skeleton (exoskeleton) shed to allow for growth, process called ecdysis

Lophophore

Crown of ciliated tentacles used for feeding

Trochophore Larva

Developmental stage, includes molluscs & annelids

Phylum Porifera

(Sponges) are sessile, filter feeders that lack true tissues

Phylum Cnidaria

Radially symmetric, diploblastic animals with gastrovascular cavity, corals, jellies,& hydras

Lophotrochozoa

Includes phyla with diverse body plans, flatworms, molluscs, & segmented worms

Phylum Platyhelminthes

Flatworms that have bilateral symmetry & central nervous systems

Do not have a body cavity/ circulatory organs, includes: tapeworms, planarians, & flukes

Phylum Annelida

Most of segmented worms live in marine/ freshwater habitats, familiar group earthworms

Phylum Mollusca

Have a soft body, protected by hard shell, snails, clams, squids & octopuses (don’t have a shell)

Superphylum Ecdysozoa

Includes more species than all other eukaryotic groups combined

Phylum Nematoda

Nematodes (roundworms) abundant in soil & aquatic habitats

Many species parasite plants & animals, tough cuticle coats their body

Phylum Arthropoda

Majority of known animals, includes: insects, crustaceans, arachnids are arthropods

Have segmented exoskeleton with jointed appendages

Superphylum Deuterostomia

Includes both invertebrate & vertebraes species

Phylum Chordata

Humans are apart of this, 90% of chordates are vertebrates

Two groups of invertebrates: Lanchelets & tunicates

Phylum Echinodermata

Marine animals bilaterally symmetrical as larvae, not as adults

Invertebrates

Animals that lack a backbone, immensely diverse, including species that are microscopic & those that are 18 m long

Phylum Porifera

Sponges, simplest animals, sedentary, mostly marine animals, range in size from millimeters—meters

Filter Feeders

Captures particles suspended in water passes through its body

Water drawn into central cavity Spongocoel & flows out through Osculum

Choanocytes

Flagellated collar cells, engulf, bacteria & food particles by phagocytosis

Mesohyl

Two layers of cells separated by gelatinous region

Amoebocytes

Totipotent cells within mesohyl that digest food, transports nutrients & make skeletal fibers

Hermaphrodites

Most sponges are, each individual functions as both male & female

Most exhibit sequential hermaphroditism

Phylum Ctenophora

Comb jellies, gelatinous, translucent plankton are spherical/ oval-shapped

Phylum Cnidaria

Diverse sessile & motile forms include corals, hydras, & jellies

Diploblastic with radial symmetrical bodies

Gastrovascular Cavity

Basic body plan sac with central digestive compartment, single opening functions both as mouth & anus

Two variations on body plan: sessile polyp & motile medusa

Polyp

Adhere to substrate by aboral end of body with mouth on underside

Cnidarians, predators that use tentacles to capture & consume prey

Cnidocytes

Unique cells used in defense & prey capture, tentacles are armed

Nematocysts

Specialized organelles within cnidocytes, eject a stinging thread

Phylum Cnidaria

Two major clades, Medusozoa & Anthozoa

Exoskeleton

External skeleton, corals, solitary/colonial, form symbiosis with algae & secrete a hard of calcium carbonate, protects the coral from rocklike reefs, provides habitats

Phylum Platyhelminthes

Includes flatworms that live in marine, freshwater, & damp terrestrial habitats

Dorsoventrally flattened acoelomates

Protonephridia

Networks of tubules with ciliated structures called flame tubes, pull fluid through branched ducts open to external environment of flatworm

Planarians

Rhabditophora, live in freshwater & prey on smaller/ feed on dead animals

Some reproduce asexually by fission, planarians are hermaphrodites, copulating mates cross-fertilize each other during sexual reproduction

Trematodes

Diverse hosts, complex life cycles with alternating sexual & asexual stages

Many require intermediate host, which larvae develop before infecting final host

Tapeworms

Parasites, mostly vertebrates, including humans, absorb nutrients directly from the host intestine, latch onto hosts intestines & extract nutrients, leaves host’s body through feces

Phylum Mollusca

Snails & slugs, oysters & clams, octopuses & squid, open circulatory system, main body cavity hemocoel

Foot

Muscular, usually for movement

Visceral mass

Containing most of internal organs

Mantle

Fold of tissue draping over visceral mass secrete the shell

Mantle Cavity

Water-filled, housing the gills, anus & excretory pores

Radula

Straplike, to scrape up food

Chitions (Polyplacophora)

Marine animals with oval-shaped & shell made of 8 dorsal plates, foot is used to grip & creep, radula is used to scrape off algae

Gastropods (Gastropoda)

3-quarters of molluscs are, move slowly using cilia/ rippling motion of foot, some use modified radula to feed on prey

Bivalves (Bivalvia)

Shell divided into 2 halves drawn together by adductor muscles, gills houses inside mantle cavity & are used for suspension

Cephalopods (Cephalopoda)

Active marine predators with beak-like jaws surrounded by tentacles, immobilize prey using poison in their saliva

Ammonites

Shelled cephalopods, once dominant invertebrate predators of the sea, went extinct

Phylum Annelida

Annelids classified under, segmented worms live in marine, freshwater, & damp soil habitats, have coelom ( no blastocoel) range from 1 mm—-3m length

Leeches

Range from 1 to 30 cm, most inhabit freshwater, some are marine & terrestrial species live in moist vegetation, predators of invertebrates, blood sucking parasites of vertebrates, slit skin of host & secrete anesthetic to prevent detection

Earthworms

Eat through soil, extracting nutrients & eliminating undigested materials as fecal castings, cross-fertilize by joining in opposite direction exchange sperm, some reproduce asexually by fragmentation & regeneration

Molting

Cuticle shed during ecdysis