MBE 230-Chapter 9: Sponges (Porifera) and Ctenophores (Comb Jellies)

Sponge Structure (Porifera) (10,000 species):

- Multicellular Choanoflagellates

- Skeletal structure of CaCO3 spicules (in shallow waters), Si spicules (deep sea), spongin, and some have a CaCO3 exoskeleton.

- Many incurrent pores (taking in water fron outside environment)

- Few excurrent pores (releases; outward flow)

- Oldest surviving species of the metazoans.

Sponge eating habits:

- They are filter feeders and feed on: Bacteria, algae, and detritus

- They can filter up to 20,000X body volume/day

- Few carnivores use external or internal mucus to get prey

- Some have external mucus or spicules on filaments where there is low food abundance.

Sponge lifestyle:

- They are benthic on hard substrates (They lay on the seafloor on hard substrates such as sand, rocks, etc...)

- They have adaptation to currents and turbulence.

- Some will bore into rocks and shells.

- Some will move a few mm/day.

- A few have "roots" on the sediment.

Sponge Life span and Reproduction:

- Roughly 10,000 species.

- They are ubiquitous: can range from intertidal to deep sea, and polar to tropical waters.

- Little differentiation; all cells independent and can fragment.

- They have an endoderm, exoderm, and internal mesoglea with amoebocytes.

- The amoebocytes can differentiate into gametes.

- They are mostly hermaphroditic, they have internal fertilization and internal development.

- They have planktonic larvae.

- Some can reproduce by fragmentation or budding.

- Their life span is about 2 years in shallow temperate waters.

- Their lifespan is about 200 years in the deep sea.

- Potentially up to 5,000 years in the tropics.

Sponge Internal systems:

- They have intercellular communication and coordination but NO NERVES.

- They use electrical pulses and neurotransmitters.

- They can also control their flow rate by actively filtering a volume of water equivalent to many times their body volume each hour.

- Most sponges have anti predation toxin; so only a few mollusks, fish, and turtles can eat them.

- They have a few microbial diseases.

- They are a primary source of useful pharmaceuticals.

- They have primitive immune systems.

- They can be habitats for 1000's of invertebrates.

- Evolutionary "dead end"

- Some species can be overfished.

Ctenophores (Comb Jellies) (100-150 species)

- They are primitive metazoans and have an endoderm, ectoderm, and mesoglea (mesoglea helps with hydrostatic exoskeleton)

- They are gelatinous; meaning they are mostly transparent but some do have pigment in the deep sea.

- Many of them are bioluminescent (Some can secrete bioluminescent ink).

- They have radial symmetry.

- They have 8 comb rows (It beats its comblike shapes to move through the water). They also have 1000's of unusual cilia up to 2 mm long.

- Largest ciliary swimmers.

- They have 2 tentacles in most cases (some without) with sticky mucus.

Ctenophore eating habits:

- They have a mouth with ciliary "teeth" and are carnivorous.

- They feed zooplankton, small fish, eggs, and larvae.

- They can eat up to 10X their body weight/day.

- They can greatly impact and alter food chains and fisheries.

- Those without tentacles can "bite" with ciliary "teeth" or engulf their prey.

Ctenophore Internal structures and systems:

- They have a general nerve net (But have different neurons from other metazoans)

- They also have statoliths (allows for balance and orientation)

- They have muscles for tentacles, mouth, and for undulating.

- They have a "dead end" digestive system, but have 2 anal pores.

- Most of them are hermaphroditic

- Mostly external fertilization, larvae or direct development.

- They are also ubiquitous; they can be in shallow and deep sea waters, and in polar and tropical waters.

- They get eaten by jellyfish, turtles and a few fish.

- They are an evolutionary "dead end" (selectively advantageous in the short term, but results in lower diversification in the future).