Monday, 16 February 2015 17:45

A Hitch Hikers Guide to the Reefs - Snails, Slugs & Nudibranch Featured

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hitchsnailsbannerBy Charles & Linda Raabe
Mactan Island, The Philippines



  Most of us think of snails and slugs as being harmless grazers of algae but the vast majority of those found as hitch hikers frequently turn out to be very predatory. Cowries are a good example.  There are very few nudibranch that are reef safe and just as the snails, those found as hitch hikers are most likely a predator with very specific prey items., If you see nudibranch for sale, please avoid buying them as they will most likely starve to death or be a predator of other life in your tank.

snailfeaturesFeatures of a snail shell. A-height, B-width, C-apex, D-suture, E-whorl, F-spire, G-columella, H-aperture margin or lip, I-position of umbilicus if present, J-body whorl (last whorl). This is a partulid shell. Like some other snails, partulids develop a "lip" around their aperture at sexual maturity. 



eggs  snaileggs1Typical snail egg laying patterns

snailspawnA snail releasing sperm into the water


  If you can find a common name family group, such as whelks, cowry and such, try this very complete Snail ID site.

  With the thousands of snail species that can be found, it would be impossible for me to list them into hundreds of family groups. Since as hobbyists, our main concern is if a specific species is considered safe to the other life forms within our aquariums, I will list the snails into only one of two categories. Either being reef safe or not reef safe. You may note that some species, normally considered reef safe, such as the Nassarius members, will be listed as not reef safe since they can be harmfull to the sand infauna, since a live sand bed is part of any reef, any animal that consumes the life found within a sand bed could not be considered reef safe. Only those species that are strictly herbivores will be listed by me as being reef safe. Please keep in mind that there are snail families that have members containing both reef safe and non-reef safe specimens, as such, you may see family members listed in both categories.


snailmouth1  snailmouthRasping mouth parts of a Herbivorous Snail



    The Cerith Snails    Harmless herbivores and Detritivores

                                                                           A Cerithium species
  cerith3   cerith4   cerith5    
        Unknown Cerithium species                        Cerithium punctatum
  cerith2   anachis

   The  Chitons    Depending upon the species of course, some are harmless algae grazers while others prey upon meatier items.
  chiton   chiton1   chiton2  Below a commonly found Cryptoplax larvaeformis, a harmless herbivore. (photos taken at night)
  chiton5   chiton6   chiton7  Below, a species that prefers to remain below the substrate.
  chiton3   chiton4

    Vermetid Snails (tubes & webs)  A prolific breeder and can become a pest.
  vermetidsnails   vermetidsnails1   vermetidsnails2  vermetidsnails3   vermetidsnails4   vermetidsnails5

     Star Snail (Astralium Calcar)  Members of this family group are the best suited for our rocky landscaped aquariums.

     Limpets  -  Members of this family group(s) are largely unknown as to their dietary needs. Some species can be omnivores and eat both plant and animal matter while others can be strict herbivores or can develop a taste for coral flesh.  If you find these snails in your aquarium, it would be wise to keep an eye on it to determine exactly what it is eating.  Some are Reef safe, others are not.   It is quite possible that these snails can become prolific breeders in our systems as they brood (keep) their eggs until fully developed. Upon hatching, fully formed tiny limpets are able to crawl away, avoiding any filtration or predators that their free floating snail cousins must endure as larvae within our systems. 

  limpet1   limpet2   limpet3  limpet   keyholelimpet

                 Trochoidea                                                  Astrea                                              Turbo Snail    
  trochus   astrea   turbo

               Euplica  versicolor                                       Conch                                          Pyrene testudinaria
  versicolor   strombus   pyrene

      The Nerites
  nerite   nerite1   nerite2

    Stomatella Varia. - A very commonly found hitch hiker. Harmless herbivore which has a unique way of fooling predators. When attacked or pulled off the glass by us, it will drop a large portion of its foot, much like some lizards that break off their tails in an attempt to keep a predator busy while it makes its escape.  Keeping to their descriptive species name, they are highly variable in colorations.
  stomatella   stomatella1   stomatella2  stomatella3   stomatella4   stomatella5  stomatella8   stomatella9  stomatella6   stomatella7

     Collinista  ( Harmless algae grazer ) 
  Collinista   Collinista1   Collinista2

      Scutus sp. -  One of the more unusual marine snails, related to limpets. Reef safe algae grazer.
  scutus   scutus1   scutus2

      Abalone  - A harmless herbivore and is distinctive by its "holes" evident in its shell. 
    Shown below is a Haliotis asinina  (  aka donkey ear abalone )
  abalone   abalone1   abalone2

    UNKNOWNS - Called as such because these animals have very little known about them. Which means I have no way to determine whether they could be considered reef safe or not, and I quote "The columbellids are probably the worst family to deal with. They are abundant and diverse and appear to mimic in shape all other snail groups." - Dr. Ron Shimek.

    Triforid sp.  -  Related to Ceriths and have very little known about them. This species is at most 1/4th inch long and as shown, has two juveniles that stay on the adult at all times. If this is parental care, that is unknown as well. 
  triforid   triforid1   triforid2

            Mitrella circumstriata                                   Mitra pica                                             Mitrella sp.
      Possible Scavenger found in live sand                                 Unknown diet                                                         Unknown diet
                                                                                Thumbnail photos of all known Mitrella species
  mitrella   mitrella1   mitrella2



   THE WHELKS - All of which are predatory / meat eaters


   Drupella Cornis ( Coral Predator )      Cantharid Whelk (mollusk,snail predator)   Coralliophila Sp  (coral predator) 
  drupellacornus   cantharidwelk   Coralliophila

   Melongena corona  ( predatory whelk)          Babylonia Whelk   (Predator)                     Coral Predator 
  melongena corona   Babyloniawelk   coralpredator

              Engina zonalis   (whelk)                        Nassarius albescens                     Another snail predator (whelk)
                                                                Reef safe except for live sandbeds
  Engina zonalis   whelk   welk1

                Bursa granularis                                 Maculotriton serriale   
  bursidae   muricidae

    Cowry Snails-  These snails can be confusing since they are rarely seen as shown in these photos, the reason they are all nice and shiny looking is that they cover their shell with a mantle which gives them a fleshy appearance, but if you touch the mantle, it will retract and show the shell beneath.  While this family of snails has members that are reef safe, there are too few of such members as to consider this family as reef safe. I will though list by name those that are reef safe when possible. 

           Ringed Cowry  (reef safe)                     Deer Cowry  ( reef safe)
  cowry   deercowry   cowriedetails     Example of Cowry snails mantle covering, of which all cowrys have in various colors and textures.
  cowrie1   cowrie2   cowrie3

   The  Triviidae  - While very cowry like in appearance, they belong to a different family. Predators upon ascidians..
  trivia   trivia1   trivia2

    The Olive snails                   
   ( While normally considered scavengers and reef safe, they can predate upon the sand infauna )
  olivesnail   olivesnorkel   olivesnail1  olivesnail2   olivesnail3

     Vexillum (Costellaria) exasperatum   Its diet consists of polychaetes and gastropods,  not sand bed or reef safe.
  nassarius   nassarius1   nassarius2

     Thyca crystallina  - A Predator of Linkia Starfish   
                                                                                                                                      The damage done by this Snail
  linkiasnail   linkiasnail1   linkiasnail2

        Heliacus  ( Zoanthid Predator)  
  heliacus   heliacus1   heliacus2

          Sun Dial  ( Philippia Radiata)        Calpurnus verrucosus (coral predator)    Primovula sp. (gorgonian predator)
  sundial   calpurnus   primovula

   Calpurnus lacteus (octocoral predator)   

     The Fasciolariids  ( Tulip Snails )

     Peristernia reincarnata, predator of other snails.
   tulip   tulip1   tulip2

    The Conidae  ( Cone Snails )

      Conus ebraeus (worm predator)
  cone1               Unknown species
  cone2   cone3


  It is not uncommon to find that other species of snails or limpets are using their much larger cousin's shell as an algae foraging area. While not harmfull to the host snail in most cases, it can however make the host snail more obvious to predators in the wild by having its algae camoflauge removed.  In the case of some limpets,  they can pose a risk to their "host" snail by boring into the shell and feeding upon the host snail.  For more information on such limpet species, please see this link.

  piggybacksnail   piggybacksnail1

Great Nudibranch Article    Anemone Predator Article


       Aplysia sp. (Sea hare)       Anaspidea species list
  seahare   seahare1   seahare2  seahare3   seahare4   seahare5

     Phanerophthalmus smaragdinus                A juvenile P. smaragdinus           Aeolid Nudibranch ( acropora predator) 

  seaslug1   slug5   aeolidnudi 

            Dendrodoris elongata                            Thuridilla gracilis                  Tritoniidae Nudibranch (coral predator)
  seaslug2  slug3  slug4

    Melibe Fimbriata  - Filter feeding Nudibranch also capable of consuming copepods
   fimbriata   fimbriata4   fimbriata5    Feeding on Copepods
   fimbriata1   fimbriata2   fimbriata3

    Placida dendritica  -  A member of the Sacoglossa. The green inside the cerata and in the ramifying ducts that extend past the eyes & along the base of the cerata are chloroplasts that it has stolen from food algae & kept alive in the body which is used much like zooxanthellae are within corals.
   slug10   slug11   slug12

          Plakobranchus ocellatus                       Chromodoris decora                              Berthellina citrina 
                                                                           ( sponge predator )                          ( coral , sponge predator )
   slug6   slug7   slug8

       Berthella stellata - A Sponge predator that defend themselves by secreting sulfuric acid. Handle with care!
   spongeslug   spongeslug1   spongeslug2

                Hypselodoris emma                         A Phyllidiid Nudibranch                              An Aeolid species
                  sponge predator                   Very toxic, will nuke your tank if it dies                 Predator of Corals
   slug9   phyllidiid   aeolid   

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Used by permission.  Many thanks to Charlies and Linda Raabe for their support.

Read 6783 times Last modified on Wednesday, 17 June 2015 03:33
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