Diversity of Eukaryotic Chapter 11- Lophotrochozoa

Bilateral symmetry

mirror images along a central axis

anterior, posterior, dorsal, ventral

Key body axes in bilateral symmetry

Cephalization

____ is the evolutionary trend of concentrating sensory organs and nervous tissue at the anterior (front/head) end

locomotion

Cephalization is an adaptation for ____ (crawling, swimming, burrowing), because animals move head-first, anterior end encounters the environment first, concentration sensory organs there improves navigation.

bilateria

Evolution of ____: sensory processing, feeding, predator avoidance, centralized system

three embryonic germ layers

divergence in animals also based in part of the development of ____ and development of mount or anus from blastopore

endoderm, ectoderm

Diploblastic : ___

endoderm, ectoderm, mesoderm

triploblastic : ____

mouth forms second from blastopore

deuterostome : ____

mouth forms first form blastopore

protostome : coelom is formed by ingression and splitting by blastopore ____

mouth forms second to blastopore = anus

deuterostomes : mesoderm and endoderm form by infolding of endoderm, ____

Coelom

____ function:

• functions as a cushion for internal organs

• allows for independent organ development and movement

• can act as a hydrostatic skeleton (flatworms)

Eucoelomate

____ = true coelom, a body cavity completely lined by mesoderm

Pseudocoelomates

____ = body cavity is partially lined with mesoderm

Acoelomates

____, lack a true coelom (a fluid-filled body cavity completely lined by mesoderm); mesenchyme provides hydrostatic support

molting

Ecdysozoa = ____

lophotrochozoa

____ = trochophore larvae, lophophore feeding, no molting

ciliated tentacles

lophophore is a feeding structure with ____.

propelled by cilia

Trochophore larvae is a larvae ____ (common in marine annelids + mollusks)

Larvae

____ is a sexually immature and morphologically distinct from parent

triploblastic lophotrochozoans

Flatworms “Platyhelminthes” are bilateral, acoelomate and ____

solid mesodermal tissue

In phylum platyhelminthes, which are acoelomate, the space between the digestive tract and body wall is filled with ____

marine, freshwater, and terrestrial

Phylum platyhelminthes there are ~ 15,000 free-living and parasitic species. What environment are these found in?

diffuse across cells due to their flat bodies

Platyhelminthes “flatworms” have no respiratory or circulatory systems instead they ____

small (<2-3 cm) and flat but some can be up to 20 cm long

Free living flatworms, endoparasitic flukes, and endoparasitic tapeworms are generally ____.

body is flattened along dorsal and ventral surfaces

Basic platyhelminthes architecture: bilateral symmetry and dorsoventrally flattened (= ____), definite head at the anterior end (“cephalization”), acoelomate, digestive tract is only internal cavity.

gases move via passive diffusion

Respiration/circulation (for lophotrochozoa) : no specialized structures for gas exchange (____): no circulatory system

large surface area

“flattened” body form of platyhelminthes provide a ____ for gas exchange

locomotion

____: outer circular and inner longitudinals body wall muscles act antagonistically against a hydrostatic skeleton.

ciliated epithelial cells

free living flatworms glide via ____ on ventral surface

adjust body movement; facilitate locomotion

outer band of circular muscles (____) and longitudinal muscles (____)

maintain shape and facilitate locomotion

dorsoventral muscles connect the dorsal and ventral tissues (____)

mesenchyme

____ fills space between the space between the body wall and digestive tract

anterior and paired cerebral ganglia and nerve cords

The nervous system of platyhelminthes is a “ladder-like” nervous system with an ____.

Galgion

____ = a mass of neurons

ocelli; auricle

Cephalization in free-living species have sensory structures on head e.g., light-sensitive eye spots (=____) and chemosensory cell (=____)

excretion of N-waste

Osmoregulations (controls balance of water + salts) and ____ in flatworms of platyhelminthes

flame + tube cells

Protonephridia (____) collect excess fluid and carry to excretory pores in the outer epidermis (similar in function to vertebrate kidney)

protonephridia

Osmoregulation by ____ in platyhelminthes

flame cell

beating of cilia draws interstitial fluid into the ____, then is filtered by a tubule, water + water passed through and excretory pure.

incomplete gut

Platyhelminthes have a ____ (single opening is the mouth and anus)

mouth > muscular pharynx > simple or branches intestine

Feeding in platyhelminthes: ____

food + nutrients reaches all cells

Branching increases surface area meaning ____

mid-ventral or anterior

mouth of platyhelminthes can be ____

sexual and asexual

Platyhelminthes have ____ reproduction

internal fertilization by exchange of sperm

Sexual reproduction in platyhelminthes: most flatworms are monoecious (= hermaphrodites) with ____.

fragmentation followed by regeneration

Flatworms can reproduce asexually by ____.

Class Turbellaria, Class Cestoda, ClassTrematoda, and Class Monogenea

Four major lineages of flatworms: ____

free-living in water and moist habitats

Class Turbellaria: ____.

middle of body’s ventral surface

Freshwater worms like Dugesia (Class turbellaria) mouth is near ____, at the end of a muscular tube like structure (=pharynx) which can be extended to catch prey.

flame cells

Freshwater worms have no anus, they use ____ for excretion

cilia over a mucous trail

Freshwater worms glide with ____. While most glife over substances, some marine species are effective swimmers.

penis fencing

Mating in some Turbellarian flatworms is called ____

father; mother

hermaphrodites with sharp double penis’s, they try to stab each other and the “winner” acts as the ____ while the “loser” acts as ____.

flukes

Class Trematoda = ____

vertebrates, arthropods, annelids and mollusks

Trematodes are endoparasites (e.g., intestinal tract) that parasitize ____.

host immune response and digestive enzymes

Endoparasitic flukes = resistant to ____

sensory and locomotive adaptations

Adaptive significance of endoparasitic lifestyle: lack ____ of free-living flatworms; anterior oral and ventral suckers.

endoparasitic tapeworms

Class Cestoda: ____

vertebrate host’s digestive tract

Class Cestoda: highly specialized endoparasites; adults live in ____.

suckers and hooks

Class Cestoda: body divided into an anterior scolex region bears ____ to attach to an intestinal wall of hosts.

mouth

Class Cestoda have no ____

proglottids

Class Cestoda: Scolex is followed by a long chain of units called ____ containing both ovaries and testes (monoecious).

no sex organs

Class Cestoda: Proglottids closest to the neck are immature = ____.

male and female sex organs

As proglottids move caudally, each develops ____, making it mature.

only eggs

Gravid proglottids = ____; this occurs after fertilization when other organs within the proglottid disintegrate and the proglottid becomes filled with eggs.

finger-like tissues (microtriches)

Adult tapeworms have no gut: the outer cells of a adult tapeworm have ____ that directly absorb digested food from the host’s intestine.

greatly increase surface area for absorption of food directly from host

Microtriches (microthrix=singular): projections from the outer tegument ____.

the segmented worm

Phylum Annelida - ____

deep sea environment

Phylum Annelida: marine polychaetes and beard worms (____), terrestrial earthworms, freshwater (mostly) leeches

16,000 species

Phylum Annelida ~ ____

collagen

Annelida have an outer cuticle of ____ secreted by epidermis

nutrient redistribution: nutrient recycling

Annelids are important in marine ecosystems. They are involved in ____ by burrowing and ingest and breakdown organic debris and contribute to ____.

native earthworms were displaced by invasive flatworms

In Scotland, fields flooded when ____.

metamerism

Key innovation with annelids: ___

repeating segments

Annelids are metameric: the body is a series of ____ or metameres (each metamere is similar in structure)

metamerism

Evolutionary significance of ____: permits greater flexibility, compartmentalization, complexity and larger size

septa

Annelids: Coelom is divided by ____ (partitions allow for independent movement of segments)

in (mostly) each segment

Components of excretory, circulatory, reproductive and nervous systems are found ____ - the complete gut (intestinal tract) runs all the way through the segments.

reduce large-scale internal circulation

Septa compartmentalize the coelom > ____.

diffusion alone insufficient

Annelids: Large body size and complexity make ____

blood stays in vessels

Annelids have closed circulatory system (____): animals have pairs of pumps or “hearts: (segmental pumps seen during dissection)

carries O₂ picks of CO₂

hemoglobin present in annelids that ___

nitrogenous wastes

blood transports: nutrients (food), ___ , O₂ and CO₂ .

forward (=anterior directions); rear (=posterior direction)

dorsal blood vessel carries blood ____ ; ventral blood vessel moves blood toward ____

diffusion

Capillaries handle exchange by ____ and connect dorsal and ventral vessels

hydrostatic skeleton

Annelid movement: the coelom acts as a ____ (fluid resists compression)

elongate segments; shorten segments

Annelid movement uses: Circular muscles (____), longitudinal muscles (_____), septa allow segments (metameres) to move somewhat independently.

muscle contraction; longitudinal contraction

Earthworms move using alternating waves of _____ using circular contraction (elongates and constricts segments) and ____ (shorten and thickens segment)

double or fused ventral nerve cord

Annelid nervous system: a pair of cephalic ganglia (“brain”) attaches to a ____ that runs the length of the animal with ganglia and nerve branches repeated in each metameree

skin and mouth

Sensory structures are in an annelids ____

increased metabolism

Annelid excretory system: increased activity requires ____ which requires more efficient excretory system to eliminate metabolic N-waste.

ciliated funnel that sweeps coelomic fluid into a coiled tubule

A pair of metanephridia in almost all segments is composed of a ____ that filters out toxic N-waste from fluid and capillary blood.

filter feeders, carnivores, herbivores, scavengers, deposit feeders (=detritivores), blood-sucking parasites (leeches

Many modes of feeding in annelids: ____

mouth (blastophore) and anus

Annelid digestion: complete gut with a ____.

compartmentalized into specialized regions

The gut of an annelid is ____ (e.g., mouth cavity, muscular pharynx, esophagus, crop, gizzard, intestine, etc.) depending on feeding habitat.

swimming trochophore

Annelid reproduction: following fertilization of a zygote: the embryo becomes a ____ larva that grows into an adult (e.g., marine polychaetes)

trochophore larva

Polychaetes have externally fertilized eggs that develop into ____

swim and/or crawl

A variety of polychaete lifestyles: ____; some with long chaete.

shoreline annelid

Nereis (common ____)