Other Reef Builders like Hydrozoans, Sponges, and Algae

Outline For Expansions

Hydrozoans
1. Habitat
  1. Hydrozoans are found in all oceans, at all latitudes. Though most are found in salt water, some species inhabit fresh and brackish water on all continents except Antarctica.
  2. Hydrozoans are found in nearly all marine habitats, except for surf zones. Many species reside in warm, shallow, salty water, probably because of the availability of food in these habitats.
2. Physical Traits
  1. Hydrozoan polyps are often symmetric, and can have a variety of shapes, including urn-shaped, conical, cylindrical, or club-shaped.
  2. Polyps can range from a few millimeters tall, to 2 meters tall, like Branchiocerianthus imperator
  3. At the base of many hydrozoan, there are hollow tubes, called stolons, which connect polyps in the same colony to each other, and allow for the transfer of food between polyps.
  4. Above the base is a ring of contractile cells called the sphincter, which can open and close as needed to isolate the polyp from the stolon, to prevent undigested food from entering the stolon.
  5. Many colonial hydrozoans are polymorphic, and have different structures for different functions. Some have large spiny tentacles for defense, some have tentacles and mouths for feeding, and some have no mouth but reproduce in the form of producing medusae.
  6. As cnidarians, hydrozoans have cnidocytes. Cnidocytes, when prompted by a stimulus, shoot out of tiny hollow tubes in hydrozoans at high speed. Depending on the species of hydrozoan, these can be used to catch prey, fight off predators, or attach to a substrate.
3. Colonial Development
  1. A founding polyp attaches to a substrate, and reproduces by budding to produce more polyps, to create a network of stolon, formed of living tissue, called the coenosarc.
  2. Some species form a single layer of polyps on top of substrate, while others will form stems of polyps coming off of the substrate.
  3. In the same way that colonial hydrozoans are polymorphic, so are the polyps that make them up.
4. Reproduction
  1. Hydrozoans, in terms of reproduction, are mostly broadcast spawners, meaning they shed gametes. In the case of hydrozoans, they mostly shed sperm and retain eggs, and release sperm attracting compounds.
  2. It is not uncommon however for both eggs and sperm to be released by the hydrozoan into the water column, and for fertilization to occur externally.
  3. Polyps reproduce by budding, either creating daughter polyps, medusae, or both. In some species medusae will reproduce by fission or budding.
5. Feeding Habits
  1. Feeding habits of hydrozoan vary greatly, with some trapping plankton with tentacles, some filter out food from the water column, and some using symbiotic algae.
6. Sources
Coralline Algae
1. Description
  1. usually pink or red, can be other colors as well (gray, green, blue, yellow, purple)
  2. various forms
  3. branching (geniculate or articulated)
  4. encrusting (non-geniculate or non-articulated)
  5. classification
    1. Kingdom: Protista
    2. Division: Rhodophyta (red algae)
    3. Class: Rhodophyceae
    4. Subclass: Florideae
    5. Order: Corallinales
    6. Family: Coralinaceae (Coralline algae)
2. Habitat/Location
  1. inhabit intertidal and subtidal coastal areas
  2. live on bedrock or other substrate
  3. also on other algae, on shells, in seagrass
  4. geniculate algae can be unattached
  5. live in range of light (depth of 0-270 m)
  6. can tolerate varying levels of water salinity
  7. do not live in freshwater
  8. popular for aquariums
3. Biology
  1. sexual or asexual reproduction
  2. mineralogy: calcite (calcium carbonate,CaCO3)
  3. this compound sometimes contains Mg as well
  4. “fouling:” sloughing off outer layer of cells
  5. compete with algae attempting to grow on top of preexisting coralline algae
  6. eliminate burrowing organisms in outer layer
  7. renew damaged tissue and reproductive cells
4. Ecology
  1. typically epiphytes
  2. promote herbivores and invertebrates
  3. algae produce chemicals that attract herbivore larval settlement
  4. provide habitat for small reef animals and invertebrates
  5. parrot fish and mollusks eat coralline algae
  6. calcite production binds reefs together
  7. crucial to the structure of reef systems
5. Environmental Significance
  1. useful for fossil dating
  2. commonly found on reefs, but reefs are becoming endangered
  3. extracted for economic use
  4. geniculate algae are especially targeted
  5. used for soil conditioner, animal food additive, pharmaceutical products
6. Sources
  1. Cabioch, J. “Morphogenesis and Generic Concepts in Coralline Algae - a Reappraisal.” Helgolander Meeresuntersuchungen Helgolander Meeresunters 42.3-4 (1988): 493-509. Web.
  2. “Coralline Algae.” Coralline Algae. California State University, Fullerton, n.d. Web. 01 Mar. 2016
  3. Johansen, H. William. Morphology and Systematics of Coralline Algae with Special Reference to Calliarthron. Berkeley: U of California, 1969. Print.
  4. Keats, D.w., M.a. Knight, and C.m. Pueschel. “Antifouling Effects of Epithallial Shedding in Three Crustose Coralline Algae (Rhodophyta, Coralinales) on a Coral Reef.” Journal of Experimental Marine Biology and Ecology213.2 (1997): 281-93. Web.
  5. Martin, Sophie. “Marine Coralline Algae.” Marine Coralline Algae. The Encyclopedia of Earth, 15 June 2014. Web. 01 Mar. 2016.
  6. Steneck, R. “The Ecology of Coralline Algal Crusts: Convergent Patterns and Adaptative Strategies.” Annual Review of Ecology and Systematics 17.1 (1986): 273-303. Web. 1 Mar. 2016.
  7. Woelkerling, W. J. M.H. Foslie and the Corallinaceae: An Analysis and Indexes. Vaduz: J. Cramer, 1984. Print.