Patella ferruginea

An epibiont is an organism that lives on the surface of another living organism. An epibiont is, by definition, harmless to its host. In this sense, the interaction between the two organisms can be considered neutralistic or commensalistic; as opposed to being, for example, parasitic, in which case one organism benefits at the expense of the other, or mutualistic, in which both organisms obtain some explicit benefit from their coexistence. Examples of common epibionts are barnacles, remoras, and algae, many of which live on the surfaces of larger marine organisms such as whales, sharks, sea turtles, and mangrove trees. The host of the epibiont is typically referred to as the basibiont.

Algae is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular microalgae, such as Chlorella, Prototheca and the diatoms, to multicellular forms, such as the giant kelp, a large brown alga which may grow up to 50 metres (160 ft) in length. Most are aquatic and autotrophic and lack many of the distinct cell and tissue types, such as stomata, xylem and phloem that are found in land plants. The largest and most complex marine algae are called seaweeds, while the most complex freshwater forms are the Charophyta, a division of green algae which includes, for example, Spirogyra and stoneworts.

Barnacles are a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and are hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile (nonmobile) and most are suspension feeders, but those in infraclass Rhizocephala are highly specialized parasites on crustaceans. They have four nektonic larval stages. Around 1,000 barnacle species are currently known. The name Cirripedia is Latin, meaning "curl-footed". The study of barnacles is called cirripedology.

In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work mainly like muscular hydrostats. Most forms of tentacles are used for grasping and feeding. Many are sensory organs, variously receptive to touch, vision, or to the smell or taste of particular foods or threats. Examples of such tentacles are the eyestalks of various kinds of snails. Some kinds of tentacles have both sensory and manipulatory functions.

A midden is an old dump for domestic waste which may consist of animal bone, human excrement, botanical material, mollusc shells, potsherds, lithics, and other artifacts and ecofacts associated with past human occupation.

The Paleolithic or Palaeolithic, also called the Old Stone Age, is a period in human prehistory that is distinguished by the original development of stone tools, and which represents almost the entire period of human prehistoric technology. It extends from the earliest known use of stone tools by hominins, c. 3.3 million years ago, to the end of the Pleistocene, c. 11,650 cal BP.

The Neolithic period, or New Stone Age, is an Old World archaeological period and the final division of the Stone Age. It saw the Neolithic Revolution, a wide-ranging set of developments that appear to have arisen independently in several parts of the world. This "Neolithic package" included the introduction of farming, domestication of animals, and change from a hunter-gatherer lifestyle to one of settlement.

Al Hoceima National Park is a national park located outside the town of Al Hoceima in Morocco. It covers an area of 480 km2 (185 sq mi), including 196 km2 (76 sq mi) of sea. The park was created in 2004 and is managed by the Haut-Commissariat des eaux et forêts et de la lutte contre la désertification.

The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide. This area can include several types of habitats with various species of life, such as seastars, sea urchins, and many species of coral with regional differences in biodiversity. Sometimes it is referred to as the littoral zone or seashore, although those can be defined as a wider region.

An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and invasive species. The International Union for Conservation of Nature (IUCN) Red List lists the global conservation status of many species, and various other agencies assess the status of species within particular areas. Many nations have laws that protect conservation-reliant species which, for example, forbid hunting, restrict land development, or create protected areas. Some endangered species are the target of extensive conservation efforts such as captive breeding and habitat restoration.

Chthamalus stellatus, common name Poli's stellate barnacle, is a species of acorn barnacle common on rocky shores in South West England, Ireland, and Southern Europe. It is named after Giuseppe Saverio Poli.

Dendropoma petraeum is a species of sea snail, a marine gastropod mollusk in the family Vermetidae, the worm snails or worm shells.

Cyanobacteria, also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name cyanobacteria refers to their color, which similarly forms the basis of cyanobacteria's common name, blue-green algae, although they are not usually scientifically classified as algae. They appear to have originated in a freshwater or terrestrial environment. Sericytochromatia, the proposed name of the paraphyletic and most basal group, is the ancestor of both the non-photosynthetic group Melainabacteria and the photosynthetic cyanobacteria, also called Oxyphotobacteria.

Coralline algae are red algae in the order Corallinales. They are characterized by a thallus that is hard because of calcareous deposits contained within the cell walls. The colors of these algae are most typically pink, or some other shade of red, but some species can be purple, yellow, blue, white, or gray-green. Coralline algae play an important role in the ecology of coral reefs. Sea urchins, parrot fish, and limpets and chitons feed on coralline algae. In the temperate Mediterranean Sea, coralline algae are the main builders of a typical algal reef, the Coralligène ("coralligenous"). Many are typically encrusting and rock-like, found in marine waters all over the world. Only one species lives in freshwater. Unattached specimens may form relatively smooth compact balls to warty or fruticose thalli.

Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation and parasitoidism. It is distinct from scavenging on dead prey, though many predators also scavenge; it overlaps with herbivory, as seed predators and destructive frugivores are predators.

Eriphia verrucosa, sometimes called the warty crab or yellow crab, is a species of crab found in the Black Sea, Mediterranean Sea and eastern Atlantic Ocean from Brittany to Mauritania and the Azores. Individual crabs have been caught as far north as Cornwall. Formerly a frequent species in the Black Sea, it has decreased in numbers since the 1980s and is now listed in the Ukrainian Red Data Book of endangered species.

Pachygrapsus marmoratus is a species of crab, sometimes called the marbled rock crab or marbled crab, which lives in the Black Sea, the Mediterranean Sea and parts of the Atlantic Ocean. It is dark violet brown, with yellow marbling, and with a body up to 36 millimetres (1.4 in) long. A semiterrestrial omnivore, it feeds on algae and various animals including mussels and limpets.

Stramonita haemastoma, common name the red-mouthed rock shell or the Florida dog winkle, is a species of predatory sea snail, a marine gastropod mollusc in the family Muricidae, the rock snails.

A gamete is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce two morphologically distinct types of gametes, and in which each individual produces only one type, a female is any individual that produces the larger type of gamete—called an ovum— and a male produces the smaller type—called a sperm. Sperm cells or spermatozoa are small and motile due to the flagellum, a tail-shaped structure that allows the cell to propel and move. In contrast, each egg cell or ovum is relatively large and non-motile. In short a gamete is an egg cell or a sperm. In animals, ova mature in the ovaries of females and sperm develop in the testes of males. During fertilization, a spermatozoon and ovum unite to form a new diploid organism. Gametes carry half the genetic information of an individual, one ploidy of each type, and are created through meiosis, in which a germ cell undergoes two fissions, resulting in the production of four gametes. In biology, the type of gamete an organism produces determines the classification of its sex.

A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.

Plankton are the diverse collection of organisms found in water that are unable to propel themselves against a current. The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucial source of food to many small and large aquatic organisms, such as bivalves, fish and whales.

In reproductive biology, a hermaphrodite is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes.

Melilla is an autonomous city of Spain in North Africa. It lies on the eastern side of the Cape Three Forks, bordering Morocco and facing the Mediterranean Sea. It has an area of 12.3 km2 (4.7 sq mi). It was part of the Province of Málaga until 14 March 1995, when the Statute of Autonomy of Melilla was passed.

Ceuta is a Spanish autonomous city on the north coast of Africa.

The Chafarinas Islands, also spelled Zafarin, Djaferin or Zafarani, are a group of three small Spanish islets located in the Alboran Sea off the coast of Morocco with an aggregate area of 0.525 square kilometres (0.203 sq mi), 45 km (28.0 mi) to the east of Nador and 3.3 km (2.1 mi) off the Moroccan town of Ras Kebdana.

The Habibas islands 35°43′29″N 1°8′00″W are located about 12 km off the Algerian coast, northwest of Oran. The islands consist of a principal island 1.3 km long surrounded by an archipelago covering a total area of about 40 ha. The highest point on the Habibas islands reaches 105 m. The islands are of volcanic origin.