euk diversity midterm

bioprospecting

using natural resources to make commercially viable products. can be good bc finding new things to make out of natural resources, but can lead to overharvesting from local economies and natural resources.

‘evolution as progress’

the idea that all living things go in a linear organization, and the best things are evolved now…. this is wrong. selection cannot predict the future, only act on what is present.

aristotles view on evolution

plants and animal are the most complex and developed organisms. they are divine and unchanged (no evolution, god created them perfect).

anton van leewenhoek ideas

father of microbiology, discovered the very small stuff around us by creating the compound microscope

carl linnaeus

thought that organisms were divinely made, but proposed naming and classifying organisms

“nested hiearchy”, naming and classifying organisms in folders of folders

created kingdom, phylum, families, etc in binomial nomenclature

What is the difference between monophyletic, paraphyletic, and polyphyletic
groups? Which group do we strive for when constructing phylogenies? How does
convergent evolution influence phylogeny?

Monophyletic: a CA and ALL of its ancestors

Paraphyletic: CA and SOME of its ancestors

Polyphyletic: decendants of more than 1 CA

We strive for

charles darwin

evolutionary view of life, organisms are related and they branch out instead of humans being the perfect form.

haeckel *

coined the term, protista, for the third kingdom of life. i.e. organisms that dont fit animal or plant.

whittaker *

proposed a fifth kingdom of life: prokaryotes in the kingdom monera, protista became the trashcan taxon

woese: *

split the monera kingdom into archaea and bacteria, and split life classification into three domain (bacteria, archaea, and eucarya, we are in eucarya)

what is the protista problem?

animal, plant, and fungi are monophyletic groups. but, protista is a paraphyletic group that has alot of randos thrown in

• protista is very morphologically diverse

eukarya domain

• most are unicellular protists

  • algae (plant like)

  • protozoans (animal like)

• true multicellular is only in animal, plant, and fungi

how to determine phylogeny

• morphological data or dna

• hypothesis based on this ^

  • molecular data is very helpful!

• ancestral traits

• derived character states

  • arise in evolutionary lineage later (new traits)

• phylogeny time scales

• trees can be overlaid on each other

homology

similar traits in organisms bc of CA

homology vs convergent evolution

homology is actually bc of sharing a CA, convergent is bc of analogous structures, similar environments evolves similar structures.

there is no shared ancestry in convergent!! independent of each other

who is the sister taxon to primates? to amphibians?

primates sister taxa is rodents and rabbits. amphibians sister taxa would be most likely primates.

primate phylogeny

is a paraphyly! prosimians, new world monkeys, old world monkeys, and apes

the monophyly: simiiformes, with new world monkeys, old world monkeys, and apes in them

• prosimians

  • before monkeys and apes

• new world

  • south and central america

  • spider monkeys, capuchins

• old world monkeys

  • baboons

  • afr and asia

• apes

  • chimps, gorillas, orangutans, gibbons

what type of group is reptiles?

paraphyletic, doesnt include birds but has snakes, turtles, crocs, etc

mono: group c

para: group A

poly: group B

which is true?

B.

geological record*

archaen eon: first cells

proterozoic eon: first euk cells

phanerozoic eon: most extensive fossil reocrd, not many good fossils

• paleozoic

  • ancient animals and life

• mezosoic

  • middle life, age of dinos

• cenozoic

  • recent life

  • mammals and birds, flowering plants

key events of geologic record *

earth formed 4.6 BYA

prok 3.5 BYA

unicellular eul 2.1 BYA

multicell 1.5 BYA

humans originated 195k YA

five mass extinctions

• extinction= period of very high species loss

• permian extinction was the biggest mass extinction (90% ocean species)

• over time, the number of taxonomic families has increased, partly bc of better fossil record

fifth mass extinction

killed the dinos! 65 MYA, main theory is that an asteroid hit the gulf of mexico, debris cloud blocked out the sun

led to dominance of flowering life forms and bird diversity afterwards

earliest animals:

edicarian fauna, 600 MYA

ground plans for animals in cambrian explosion*

540 MYA in cambrian explosion, 100 diff animal phyla evolved

many are now extinct, abt 99% of all animals extinct

organisms were weird looking, evolution was experimenting lol

early plant life and sig

475 MYA on land, now there is 290k living species

sig: supply oxygen, base of land animal chains, not live without it

mosses were early land plants and dominant in first 100MY

when did vascular plants diversify

350 MYA, caroniferous time. created the coal!!! early tetra like reptiles and amphibians lived in these

primary endosymbiosis

when a larger host engulfs a prokaryote

• first

  • created heterotrophic eukaryotes with hetero prokaryote

  • became the mitochondria!

  • also infolded and made the nuclear membrane, not as important

• second

  • created autotrophic eukaryotes! plants

  • the new heterotrophic euk engulfed a photosynthetic prokaryote

  • created the chloroplast

• these are both primary endosymbioses bc the prokaryote was directly engulfed by a host cell!!

evidence for primary endosymbio

prok and mitochondria/plastid:

• similar sizes

• have binary fission

• single circular chromosome

• internal membranes

prok and euk similarity

• RNA and DNA as genetic material

• ribosomes

• lipid bilayer cell membrane

• similar amino acids and sugars

in what supergroup did 2nd primary endosymbio happen?

archaeplastida! this has red and green algae and ALL land plants in it

NOT BROWN ALGAE!

what performs photosynthesis with secondary endosymbiosis

kelp AKA BROWN ALGAE (multicell marine)! not any of the other stuff, just some protists/euk like euglena and dinoflagellates (red tide plankton AND zooxanthellae)

secondary endosymbiosis

• evolution of protists with plastids

• a larger host engulfing a eukaryote with photosynthetic thing in it already

  • indirectly got photosynthesis too

• led to other photosynthetic eukaryotes aka protists!

  • euglena

  • dinoflagellates

  • brown algae

archaeplastida supergroup*

• primary endosymbionts!!

• red algae

  • red pigment absorbs blue light, can grow in deep waters

  • coastal tropical waters

  • caco3 corraline type is a reef builder

• green algae

  • aquatic, fresh and saltwater but also on land (think its on koalas)

  • can be unicell, multicell, colonial

  • includes chlorophytes and charophytes!!

    • charophytes are sister taxa to land plants

five euk supergroups*

• protists are spread out across all supergroups

• funig and animals are in unikonts

• basal polytomy

  • the root of all euk is unknown

• archaeplastida

  • where land plants emerge (sister taxa to charophytes)

  • photosynthetic organisms

  • primary endosymbio

  • where secondary endosymbionts STOLE the chloroplasts from

• excavata (1)

• chromalveolata (2)

• rhizaria (3)

• archaeplastida (4)

• unikonts (5)

moss

a true bryophyte is an actual moss!!! other things that flower and have vascular systems or ferns are NOT moss

excavata supergroup

• unicellular protists

• share similar cell structure

• some photosynthetic

  • euglena

• some lack mitochondria bc endoparasitic

  • O2 poor environments

  • lost the mitochondria

  • diplomonads and parabasalids

chromalveolata supergroup*

includes two supgroups

• first grouped together bc of morphology, but then confirmed by molecular data

• alveolates

  • diverse unicellular

  • dinoflagellates

    • marine plankton: red tide and zooxanthellae

  • apicomplexans

    • parasites of humans and other animals (malaria, toxoplasmosis parasites)

  • ciliates

    • unicell heteros

    • have an oral groove like a mouth, repro by conjugation

    • ex: paramecium

• stramenopiles

  • mostly photosynthetic algae

  • brown algae

    • “seaweed”

  • diatoms

    • silica walls

    • photosynth marine plankton

  • oomycetes

    • decomposers or parasites

rhizaria

• amoebalike with threadlike pseudopodia to move and capture prey

• marine and fresh water plankton

• extend thru openings in shell

• forams

  • pseudos extend thru CaCO3 shell

• radiolarians

  • pseudos radiate from a silica shell

what is this

chromalveolata, is a diatom (stramenopile), secondary endosymbiosis, close to brown algae

what is this

rhizaria, is a foram.

what is this

in supergroup excavata, is a euglena. secondary endosymbiosis!! euglena are not related to brown algae!!!!

A.

what type of group is green algae?

paraphyletic. it includes chlorophytes and charophytes, but NOT land plants which it also shares a common ancestor with.

land plant traits shared with charophytes

• synthesizing cellulose in cell walls thats different from other algae

• phragmoplast forms in cell division

  • group of microtubules

  • cell plate develops to make cell wall`

what are embryophytes and why

they are land plants! 475 MYA moved to land

called that bc they are adapted for terrestrial life, mainly reproduction adaptations

adaptations

diversification of land plants and key events*

charophyte—> non vascular bryophytes aka moss —> seedless vascular (ferns) —> seeded vascular (cycads, then angios)

1. origin of land plants at start of embryophytes with bryos

2. vascular system evolved aka xylem and phloem with seedless vasculars

3. origin of seed in angio and gymno evolution with seeded vascular

xylem and phloem

xylem

• transports water

phloem

• transports nutrients

they are vacular tissue, evolved after bryos and distinguish a lot of land plants.

bryophytes*

NOT monophyletic, idk.

small, herbaceous, non woody

needs to live near water and get watered a LOT bc reproduction is still tied to water sperm swims to egg

• liverworts

  • liver shaped

  • sporophytes are small (no photo)

• hornworts

  • small, not a lot

  • sporophyte does photosynthesis with horn thing

• moss

  • more common of bryos

  • elevated sporangia capsules for spore dispersing

  • largest bryo group

  • sporo no photo

lycophytes and pterophytes*

known as the seedless vascular plants, ferns baby

larger, herbaceous, and non woody

• adaptations:

  • water for reproduction still with flagellated sperm, need moist habitats

  • vascular tissue finally!

    • xylem cells have lignin for strength

      • grow taller and get water and nurtients from soil bc of it

  • true leaves!!! light for photosynthesis

• lycophytes

  • fern allies like club “mosses”

  • microphyll, spine leaves

• pterophytes

  • larger megaphyll

  • ferns, horsetails, whisker ferns

advantages of being a seed plant (and land) *

• much smaller ovules and pollen

  • develop in the parent and protected from the environment

• pollen widely dispersed

• sperm not dependent on water

• seeds protect, disperse, and feed embryos (with cotyledons)

• allow embryos to remain dormant for years

vascular seed plant categories

• gymnosperms

  • naked seeds

  • conifers, cypress

  • are earlier in fossil record in mesozoic

• angiosperms

  • flowering plants

  • seeds aka ovules in ovaries that make fruit'

  • came to dominate plants later (now soooo many)

gymnosperm phyla*

• conifers

  • largest phylum

  • cold climates, most are evergreen

  • needle like leaves for H2O loss

  • antifreeze sap during the winter

• cycads

  • dioecious (M and F separate plants)

  • second larhest

  • oldest known plant w insect pollinators

• ginkgos

  • 1 species…

  • maidenhair tree

  • dioecious, male plants for landscaping

• gnetophytes

  • has sp. in Welwitschia with sp. in desert that has some of largest and oldest leaves

  • some ephedra plants for medicinal purposes

angiosperm flower struc

• flowers create fruit from ovary

• flower

  • petals (modified leaves)

  • sepal (leaf thing)

  • male

    • stamen

      • anther

      • filament

  • female

    • carpel

      • stigma

      • style

      • ovary!!!

        • ovules aka seeds inside

different angio fruits

• fruits are mature ovaries that disperse seeds

• fleshy

  • tomato, apple, orange

• dry

  • nuts, beans, pea pods, grains

• have wind water animal adaptations for dispersal (winged, edible, hairy)

angiosperm groups* eh

• monocots

  • think: grass, one leaf thing

  • 1/3

  • 1 cotyledon

  • fibrous roots

  • parallel leaf veins

  • vascular bundle scattered

  • floral organ in 3s

  • 1 pollen grain opening

• eudicots

  • 2/3

  • 2 cotyledons

  • taproot (think: carrot! you like eating carrots, and cant just have one)

  • veiny leaves

  • vascular bundle ring (carrot is circular lol)

  • floral organ 4s or 5s

  • pollen grain 3 openings

monocot diversity

¼ of angios are monocots,

like orchids, palms, lillies, grasses, and corn. no secondary growth, more conservative in form too. leaves w central vein like pothos, monstera

eudicot diversity

• 2/3 of angios

• small herbaceous flowering plants, woody shrubs, trees

• similar forms by convergent evolution in diff lineages

angiosperm families

• asteraceae

  • eudicot

  • sunflower family

  • 22k sp.

• orchidaceae

  • monocot, 20k sp.

C.

Unikonts supergroup (5) *

• amoebozoans

  • slime molds and typical amoeba

  • have lobe or tube shaped pseudopodia to move and engulf prey with phagocytosis

  • slime molds

    • function like a giant amoeba, creates most efficient pathways in cities similar

• opisthokonts

  • fungi, animals, and protistan relatives

  • fungi relative

    • most related to nucleariids

  • animal relative

    • most related to choanoflagellates, sister taxa

    • most likely colonial choano led to multicell animals (sponges are simplest animals, similar to colonial)

  • suggests multicell arose independently in fungi and animals

    • also fungi closer related to animals than plants

fungi groups

*

• chytrids

  • aquatic to infect amphibs,

  • flagellated spores

• zygomycetes

  • fast growing bread mold

• glomeromycetes

  • soil mycorrhizae

• ascomycetes

  • yeasta, truffles, morels, penicillin

• basidiomycetes

  • puffballs, shelf fungi

  • fairy rings!!

parasitism

• sexual parasitism

  • orchid flower looks like wasp, attracts male wasps so it gets pollinated

• zombie parasitism

  • cordyceps parasites

  • fungus invades ant body, keeps brain intact and controls muscles, gets fungus to place for spore release

animal diversity is mostly

arthropods! vertebrates only 5%, mammals are even less, humans are even less

evolutionary constraint

selection can only act on existing variation, mutations are most successful with minor changes!!

animals cant change body plan as much and must retain body form, plants can modify it more

• closely related animals look similar, distant look distant

• plants can look v different and be similar

hox gene expression

changes the body form in animals

• changes gene expression patterns, known as a master hox gene

  • can make major changes

  • can lead to presence or absence of limbs\

  • having more copies makes more diverse body changing

what is animal lineage called

metazoa

• parazoa

  • sponges :p

  • cell organization and they are asymmetrical!

• eumetazoa

  • everything else

  • tissue organization

  • radiata

    • radial symmetry

    • jellies

  • bilateria

    • bilateral symmetry

    • a bunch more everything else

how do sponges meet animal requirements

• multicell (kinda colonial tho)

• heterotrophic

• diplontic

• hox like homeobox genes

• collagen

sponge organization* w classes

based on spicule morpho

• spicules are hardened structures on sponge providing support

• calcera

  • calcerous (CaCO3) spicules

  • small sponges

  • 3 body types

• hexactinellida

  • intermediate syconoid and leuconoid

  • deep sea and polar

  • silica spicules

• demospongiae

  • all leuconoid

  • 90% of sponges

  • silica spicules, but body of spongin

• homosceloromorpha

  • few spicules

  • encrusting sponges

  • in marine caves

  • larvae may have epithelial tissue

cnidaria

• tissue organization only!!! bilateria has actual organs, these dont

• can be polyp

  • cylindrical

  • radial symm

  • sessile, some can move (like anenome), or stuck like coral

• medusa instead

  • umbrella upside down shape

  • most are jellies

  • tentacles surround mouth/anus

cnidaria classes*

• hydrozoa

  • conspic polyp phase, colonial

  • man o war, poylps in a clump

• scyphozoa

  • true jellyfish

  • conspic medusa phase, small polyp

• anthozoa

  • sea anenomes and coral

  • large polyp, medusa absent

  • radial symm

• cubozoa

  • box jelly

  • conspic medusa, poylp is unknown

bilateria into protosomia then… *

protosomia

• lophotrochozoa

  • trochophore larvae or lophophore feeding structure

  • outer cuticle NOT shed

• ecdysozoa

  • outer cuticle is molted as organism grows

protosomia vs deutersomia:

• protostome

  • blastopore becomes mouth

  • wormy things and clams and insects etc

• deuterosome

  • blastopore becomes anus (we talk shit)

  • us and other vertabrates

phylum platyhelminthes classes*

• these are the flatworms!

• first evolved as complex free living, then some lost complexity and became parasitzing, lost traits

• classes

• polycladida

  • marine, branches gut

  • brightly colored, lives with other orgs

• tricladida

  • free living in moist habitats

  • freshwater: planaria!!

  • cilia to glide over mucus

  • terrestrial and marine

• trematoda

  • Endoparasitic flukes with two hosts

  • Lack sensory and locomotive adaptation

  • A lot of body is a strong sucker to hold onto host, and reproductive structures

  • 2 host life cycle, needs to reproduce

• monogenea

  • Ectoparasites of fish

  • Similar to trematoda but only have 1 host

• cestoa

  • Highly specialized tapeworms,

  • Endoparasitic

  • Live in host digestive tract, no mouth

  • Scolex with suckers/hooks for attaching

  • Proglottids for reproduction

minor molluscan classes*

• Scaphopoda

  • Deposit feeders

  • Related to bivalves?

  • Tusk or tooth shells

• Polyplacophora

  • Chitons

  • Grazing herbivores

  • Found in shallow marine waters

  • Multipart shell, body isnt segmented 

  • Distantly related to other mollusca

  • The lil snail guys at tide pools

• Monoplacophora

  • Living fossil taxon

  • Single shell

  • Uncertain place in phylogeny 

  • Live in deep sea 

• Aplacophora

  • Deep sea, lack sea shell

  • Distantly related to mollusca

HAM! hypothetical ancestral mollusc *

• head:

  • sensory organs, mouth

• foot,

  • muscular, allows for movement

• visceral mass (body):

  • digestive, reproductive, circulatory organs

• mantle tissue

  • secretes the shell

  • encloses mantle cavity that has the ctenidia (gills)

3 major molluscan classes HAM explanation

• gastropoda

  • looks most like model

  • snails, slugs, nudibranchs (which lost shell)

  • body has torsion, shell coils

• bivalvia

  • scallops, clams, oysters

  • shell is bivalved (2 piece) with hinge and muscle

• cephalopoda

  • octopus, nautilus, cuttlefish

  • foot is lobed into tentacles

  • highly developed head

  • complex eyes and multiple brains

  • shell is reduced, used for beak??

annelida description

• originated as marine, evolved terrestrial and parasitic

• comprised of segmented worms!

• moist outer cuticle like flatworms of collagen by epidermal cells

  • NOT MOLTED

• burrowing detritivores

  • recycle nutrients in soil

  • terrestrial ones soil

• wormies!!

annelida classification*

• polychaeta

  • marine

  • most in substrate

  • tubeworms, xmas tree worms! beard worms near thermal vents

  • represents ancestor of phylum

• oligochaeta

  • earthworms and relatives

  • leeches :(

    • ectoparasites

    • salivary glands w anesthetic and anticoagulant in medicine

rotifera (in lopho)

wheel animalcules

• wheel on head (corona) is cilia used for collecting food

• smallest animals

• in freshwater and moist places, some saltish

nematode diversity

• small size and similar appearances of dumb worms

• diversity poorly known

• lives in ALL environments

  • dauers may be able to survive frozen for thousands of yrs

• many different nematode groups

  • plant parasites evolved least

  • vertabrate parasites

  • invertabrate parasites evolved most

  • sig: there is variation when parasitism evolves

panarthropoda!!*

• arthropods and two related phyla: onychophora and tardigrada

  • ALL have paired appendages

  • ALL molt their cuticles (remember water bears use it to hold eggs)

  • onychophora

    • velvet worms

    • unjointed legs on each segment

    • traps prey with slime

    • molt cuticle

  • tardigrada

    • water bearssss

    • 4 pairs unjointed legs with claws

    • molt cuticle

why are arthropods so successful ***

• various tagmatization

  • specialization

• jointed appendages

  • complex movement

• differences in appendage specialization

  • walking, flying, swimming

• hard exoskeleton (protection)

phylum arthropod phylogeny*

subphylums

• trilobita

  • extinct trilobites

  • TRI-lobed longitudinally

  • oldest arthropods

• chelicerata

  • two tagmata: cephalothorax and abdomen

  • class merostomata

    • horseshoe crabs

    • carapace and book gills

    • no mandibles

  • class archnida

    • spiders, scorpions, ticks

    • no mandibles

    • book lungs

• myriapoda

  • centipedes

  • least diverse arthros

• crustacea (paraphyletic bc of insects)

  • insects, crabs

• hexapoda

horshoe crab blood

has hemocyanin, blue blood! carries the oxygen in blood. antibiotic properties, used for testing vaccines for bacteria.

mites

all environments! they live in our eyebrows, eyelashes, etc

arthropodization characteristics*

• has an outer hard exoskeleton of chitin, protein, and caco3

• paired jointed appendanges

• major body cavity

• has tagmosis

  • grouping of segments into specialized body region

  • like head, thorax, body, and abdomen

tagmata

body regions with specialized functions. differentiated for eating, walking, swimming, flying

• little tagmosis

  • millipedes and centipedes, similar body pieces

• high tagmosis

  • insects with head, thorax, and abdomen

chelicerata classes

• • two tagmata: cephalothorax and abdomen

  • class merostomata

    • horseshoe crabs

    • carapace and book gills

    • no mandibles

  • class archnida

    • spiders, scorpions, ticks

    • no mandibles

    • book lungs

    • spiders

      • spinnerets for silk glands, making webs and enclosing prey

    • scorpions

      • chelicerae are the mouthpiece, not pincers

      • pincers are actually pedipalps

    • ticks

      • fusion of cephalothorax and abdomen, sucks blood!

myriapoda subphylum*

• least diverse arthro group

• two tagmata: head and trunk

• traits shared btw myriapoda and hexapoda

  • thought to be related, but now eh

  • 1 pair antennae

  • 1 pair of mandibles

  • 2 pairs of maxillae (mouthparts)

  • mostly terrestrial adults

• class chilopodia

  • active predators

  • centipedes!

  • body is flattened dorsoventrally

  • one pair appendages per segment

  • 1st segment has poison claws

• class diplopodia

  • millipedes!!!

  • herbivores and detritivores

  • body is cylindrical

  • some secrete defensive toxic fluids

  • two pairs of appendages per segment

crustacea subphylum*

• 30k living species

• two pairs of antennae (cheli have none, myria 1)

• greatest diversity of diff body plans among arthropods

  • lots of tagmosis

• tagmata include a head and thorax (may be fused), covered by carapace, and an abdomen

• classes

  • remipedia

    • primitive, little tagmosis

  • branchipodia

    • fairy and brine shrimp

    • planktonic form

  • cirripedia

    • barnacles

    • sessile adults with calcerous plates

    • uses cirri to trap small food aka suspension feeders

    • most are hermaphrodites

    • lacks gills!

  • malacostraca

    • crayfish, lobster, crabs, true shrimp

    • specialized appendages!!

D.

why are insects so diverse?

• outer strong exoskeleton

• 3 tagmata body plan

  • highly special feeding appendages (butterfly proboscis)

• capable of flight

  • disperal to new habitats

  • search for mates and food easier

  • escape from adverse conditions

• short generation time

• metamorphosis

  • life stages of same bug dont compete

• sensory, behavior, and communication modifications

• co evolutionary interactions with other organisms, like plants

mdoes of insect development

• ametabolous

  • no metamorpho

  • juveniles resemble adults and have molting until adulthood

• hemimetabolous

  • incomplete meta

  • juvenile wingless nymph goes thru instars

  • adults dont molt, have wings, reproductive

• holometabolous

  • complete meta

  • butterflies, bees, moths

  • wormlike wingless larvae goes thru instars

  • larvae makes non feeding pupa, tissues re differentate and emerges as an adult

organization of class insects*

• based on wings and mode of development (amet → hemi -→ holo)

• wingless insects

  • apterygota

  • first insects

  • ametabolous

• ancient winged

  • wings cant fold

  • pterygota: odonata

  • dragonflies, hemimet

• folded wings, hemimet

  • exopterygota

  • wings out OUTSIDE

  • termites, grasshoppers, mantis

• folded wings, holo

  • endopterygota

  • wing buds on INSIDE

  • butterflies, bees, moths

** ig write this on paper :(

D.

how to remember deuterostome?

means second mouth. during gastrulation, blastopore first becomes the anus (we talk shit), and mouth forms secondarily

in protosomes the mouth develops from the blastopore, and the anus does too

protostome vs deuterostome differences*

• cleavage

  • proto= spiral and determinate cleavage

  • deuter= radial and indeterminate cleavage, cells are totipotent for longer

• coelem formation

  • proto= schizocoelous (split) coelom formation

  • deuter= enterocoelous formation

• blastopore becomes

  • proto: mouth

  • deuter: anus, mouth forms separate

sea cucumbers

weird stuff

• Symbiont: 

  • pearlfish lives symbiotically inside their anus…

  • Worms, crabs, snails, are commensal and leave the anus at night to feed

  • Other symbionts are parasites and eat the organs (but can be regenerated)

• Defense and regen

  • When provoked, sea cukes defensively discharge organs thry anus to deter predators

  • Bc organs sticky and toxic, like cuverian tubules in respiratory tree