zoology ch.3 phyla of uncertain affinity

Placozoa, Ctenophora, Rhombozoa, and Orthonectida are considered phyla of uncertain affinity because

their phylogenetic positions within the animal kingdom are debated, with molecular and morphological data sometimes conflicting on their evolutionary relationships to other groups

placazoa moving mechanisms

ciliary gliding

Trichoplax adherens

discovered in a saltwater aquarium in 1883

placozoa are thousands of cells organized in

a double layer, an upper epithelium and a lower epithelium

what orientation do placozoas have

Dorsal-ventral orientation

in placozoa, dorsal cells are

flattened, monociliate with lipid droplets

in placozoa, ventral cells are

columnar with NO lipid droplet

in placozoa, ventral cells can

invaginate (feeding?)

placozoa have mesenchymal middle layer

with amoeboid cells in gel matrix

placazoa perform asexual reproduction via 

binary fission

placazoa are assume to have sexual reproduction because

eggs have been seen

what is depicted here 

a placozoa 

phylum Ctenophora are coomonly called

comb jellies

ctenophores have Ctetnes, meaning they have

comb rows

ctenophora germ layers

Diploblastic, but maybe triploblastic

in ctenophores musculature is formed by

mesenchymal tissue

some ctenophores have

colloblasts

ctenophores are the first phylum to have

anuses

ctenophores have how many anal pores

2 anal pores

ctenophores have a nervous system that is compromised of a

nerve net

ctenaphores are more complex than 

cnidaria 

ctenophores do not have which of the following systems

respiratory, excretory or circulatory

ctenophores have no alternation of generations, meaning they are

monomorphic

monomorphic

existing in one form (little to no morphology)

ctenophores are monoecious meaning they are 

hermaphrodites (having both the male and female reproductive organs in the same individual)

what is depicted here

phylum ctenophora (comb jellies)

what is depicted here 

ctenophores comb rows 

ctenophores are various carnivores, meaning 

they would eat each other 

what is the arrow signaling to 

Ctenophora colloblasts 

what is the function of colloblast in ctenophora

prey capture 

grade mesozoa was formally

a phylum

grade mesozoa is now divided into which two phylums

Orthonectida, Rhombozoa

grade mesozoa was considered the “missing link”

between the protozoans and metazoans

the organization of the grade mesozoa is very 

simple 

why is the organization of grade mesozoa simple 

it includes ciliated, minute, worm-like organisms 

grade mesozoa is encompassed with how many cells

20-30 cells only in 2 layers

grade mesozoa is compromised of all _ of marine organisms 

endoparasites (live inside a host's body and can cause symptoms including diarrhea, malnutrition, and organ damage)

Phylum Orthonectida are poorly 

understood

Phylum Orthonectida have how many families

2 with around 20 species

Phylum Orthonectida body structure

single layer of ciliated outer cells surrounding a mass of sex cells

Phylum Orthonectida are dioecious, meaning they are 

gonochoristic

gonochoristic

species with separate sexes, where each individual is either male or female and remains that sex throughout its life

Phylum Orthonectida have hosts meaning that they are 

parasites 

Phylum Orthonectida that swim freely in hosts

Echinoderms, Annelids, Platyhelminthes (flat worms), Bivalves

Phylum Orthonectida and Phylum Rhombozoa reproduction strategy

sexually and asexually 

Phylum Orthonectida reproduction starts with 

internal fertilization

Adults leave host and sperm leaves male and penetrates female

in Phylum Orthonectida, after internal fertilization

Zygote is ciliated larva and leaves female to find new host

in Phylum Orthonectida, after larva found a new host

Larva loses cilia when enters host and becomes a syncytial plasmodium

in Phylum Orthonectida, after larva becomes a syncytial plasmodium 

Plasmodium breaks up into new adults

Phylum Rhombozoa is also called

Dicyemida

in Phylum Rhombozoa asexual found in

immature/juvenile hosts (Cephalopods)

in Phylum Rhombozoa, asexual forms are

nematogens

in Phylum Rhombozoa, asexual organisms produce

vermiform larva

in Phylum Rhombozoa, organisms produced by asexual organisms undergo

direct development and form more nematogens

in Phylum Rhombozoa, sexual organisms produce

infusiform larva

in Phylum Rhombozoa, larva released in

urine of host

in Phylum Rhombozoa, products of sexual organisms parasitize

very few species of Cephalopods